Chewbacca and R2D2: Secret Rebel Agents
R2 manages to not have his memory deleted (like 3PO does) at the end of Episode III and becomes the perfect poker-faced spy. When Episode IV starts, Leia doesn't have the secret plans, R2 does. She just sends along a message to Obi Wan. Things go awry when the Empire gets in the way, so R2 gets in the escape pod knowing he can get down to Tatooine and Obi Wan. Originally the plan was to pick him up on the way to Alderaan, possibly with Luke in tow, who Obi Wan has been watching over for 20 years - its in the book, folks. 3PO is the one hesitating to get into the escape pod, but R2 knows they've gotta do it to get to Obi Wan.
They land, and R2 purposefully gets captured by the Jawas and negotiates with them to take them to Obi Wan. The Jawas only agree to take them to the Skywalker farm, because there's Sandpeople near Kenobi. R2/3PO are purchased by Luke & Owen/Beru Lars, and as soon as he can R2 heads off toward Kenobi's. Upon discovering R2/3PO/Luke being attacked, Kenobi calls R2 "my little friend", which he is, they've known eachother since Episode I. He says "I don't seem to remember ever owning any droid" as a signal to R2 to shut up around Luke. Before bailing to Tatooine, but after being intercepted by the Empire, R2 dispatched a signal to his fellow super spy Chewbacca that said something along the lines of "Uhh, we might need a ride to Alderaan, can you pick us up at Mos Eisley?" Meanwhile, Chewbacca gets the message and makes a "mistake" forcing Han to dump his cargo and high-tail it to Tatooine, which gets them there on time to pickup R2/3PO/ObiWan/Luke.
Chewbacca really runs the whole smuggling thing, not Han. Han's just a pilot, and in fact the Falcon's not his ship, its really Chewies (thats why it makes the above cameo in Episode III, see the tiny ship just off the edge at the bottom?). Chewie sets up the deals and Han haggles the price, giving Chewie free reign to pick where they go, which lets him deliver Rebellion intelligence anywhere in the galaxy at ease under his cover. This is exactly what happens in Mos Eisley, Chewie and R2 and Obi Wan know what's going on, but Han, Luke and 3PO are along for the ride.
Think about that scene in Mos Eisley. Obi Wan walks right up to Chewbacca before 3PO and R2 are even thrown out of the cantina. That was fast, eh? So they all head to Alderaan, its not there, they sneak onto the Death Star, and when R2 finds out Leia is there Chewie helps convince Han to go along with Luke's rescue plan. Then as they escape, Obi Wan is forced to sacrifice himself as a distraction, leaving Chewie and R2 (and Yoda) the only characters alive that know about Luke, Leia and Vader's family tree. Chewie sees Luke and Leia feel drawn to each other, and realizes thats just wrong... just wrong, and so he plays incest-cop and shoves Han at Leia. When they get to Yavin, Chewie agrees to bail with Han because if Yavin is destroyed he'd be the only one who could try to salvage the Rebellion and find Yoda. Apparently Yoda has been communicating with Obi Wan through the ghost of Qui Gon Jin, but since Obi Wan's dead now, their only link to Yoda is Luke (who Ben can ghost-chat with). And since Bail Organa got blown up by the Death Star on Alderaan, things are looking pretty grim. R2 has the Death Star plans they need to take thing down, not Leia. Then Han changes his mind, Chewie is thrilled to go back and fight, and they save the day.
If you notice in the medal scene, Chewie is not medaled, he turned it down because he got one from Yoda like 20 years ago, but he can't really mention that, now can he? So now the leaders are all gone or out of contact (Yoda) and Leia, the daughter of Vader, is in charge.
Jossed: Unfortunately. Too many canonical Star Wars books disprove this theory.
Un-jossed?: Star Wars books and the AU at large now declared non-canon.
The Emperor And The Yuuzhan Vong Invasion
The Emperor wasn't spending all those resources creating crazy superweapons like the Death Star and the Sun Crusher and putting together gigantic fleets of Star Destroyers wasn't to stop the Rebel Alliance, but rather in preparation of the Yuuzhan Vong Invasion that would happen about a quarter century after RoTJ ended.
Now the Emperor was a competent man. He was elected to Chancellor of the Republic, started a war, earned himself absolute control on both sides of the war, then managed to turn the galaxy against the guys who for a millennium had served as icons of peacekeeping, justice, and democracy. And that takes some serious strategizing! But here's the thing:
At this point, the Republic was falling apart, with or without a Sith-led Separatist movement to nudge them in the wrong direction. The senate was a hung jury where nothing ever got done. Corruption ran rampant, and even the Jedi Council wasn't doing it's job properly. Ideally, Jedi are supposed to act as bastions of compassion and moderation. The way the Jedi would be tasked to deal with a situation is as a balancing influence between, say, two conflicting nation-states, or a particularly quarrelsome trade agreement. Everyone respected and would listen to a Jedi, and even without acting on behalf of the Republic, they should be able to arrive on a scene and be able to allow discussion and bureaucracy to flourish. Instead, the Jedi Council of the waning days of the Republic had grown inward and conservative, spending all their time meditating on the state of the galaxy and not enough time heading out there and fixing the problems that needed fixing. This held throughout the war, when Jedi were surprisingly quick to jump to open combat as opposed to discussion.
In short, the Republic was completely and utterly unprepared for a real invasion, from a force that wasn't being controlled by a puppetmaster who was preventing either side from gaining an advantage until the moment was right, but rather an actual threat. The kinds of fleets that were commonplace in the Empire would have been impossible for the Republic to even agree to create, let alone have the wherewithal to actually build. What Emperor Palpatine did was take a failing system and tear it out by the roots, replacing it with a brutally efficient, military-industrial focused society - one that could adequately prepare for an invasion of the scale of the Yuuzhan Vong were already beginning.
Second of all, if you think about it, creating a weapon that can destroy planets doesn't make a whole lot of sense when you're fighting a war against a well funded, but decentralized and scattered rebellion. The Rebel Alliance wasn't fighting a war of planets or borders or resources, they were fighting a war of attrition. What good is the ability to destroy a planet when your enemy doesn't even officially control any? The destruction of Alderaan, the only notable use of the Death Star, was a move made by Grand Moff Tarkin, whose Tarkin Doctrine, though it heavily influenced the way the Empire kept a tight grip on even the furthest systems, was not the ultimate purpose of the "ultimate weapon". Tarkin was convinced that the Death Star was his tool, one of intimidation and despotism, that he could use it to keep the Alliance, the biggest threat to his power, at bay. And we all know how that venture turned out.
No, the real purpose of the Death Star was to be able to fight a force that could completely terraform an entire planet into a gigantic, organic shipyard in a matter of months, and was backed by dozens of 100+ Kilometer across worldships. In fact, without the timely arrival of the seed of the original Yuuzhan Vong homeworld, Zonama Sekot, and a Jedi-influenced heretic cult that spurred a slave uprising, it's very unlikely that the denizens of the galaxy could have survived the war at all under the leadership of the New Republic. In fact, it's not really even fair to say that they "won" the war in any sense, with a sizable portion of the population of the galaxy eradicated, Coruscant, the former shining jewel at the heart of every major government for millennia, captured and terraformed beyond recognition, and the New Republic forced to reconstruct itself as the Galactic Alliance. Undoubtedly, for all it's flaws, the Empire could have hammered out a far less Pyrrhic victory over the Vong. And if Emperor Palpatine hadn't underestimated the abilities of both the rebellion he never considered a comparable threat, and one young Jedi, perhaps the galaxy could have avoided the deaths of uncountable sentients during the Yuuzhan Vong war years later.
Han Solo is A Jedi Master
This is a little far-fetched, but hear me out...
Pre Star Wars 7 Theory
As many have seen the newest Star Wars movie, The Force Awakens, this is basically a sort of "What-if?" As many of you will often hear when you read these types of things, that this is a "Spoiler Elert" so stop reading if you haven't seen the Movie!
Now that that is out of the way, let's get into my theory. Okay, why did Luke put himself into Exile, and why was he not there when the Jedi school was attacked by the Knights of Ren. I believe that this answer is two-fold. I think that he was there when the school was attacked but he fled. That would explain why he put himself into exile. For not staying, and thus letting so many children die. But why would the founder of that school flee when it was being attacked? I think that the reason is simple: LOVE! In the three visions that Ray had when she first touched the lightsaber, the 1st was a vision of basically the last time that it had been wielded by Luke Skywalker (it having been constructed by Anakin Skywalker himself). The third was a vision of the future where she would have a battle with Kylo Ren. The middle part was a vision of the attack on the Jedi Academy, that the lightsaber should have had no knowledge of. But, what if this wasn't a vision from the 'saber's past, but from the past of the one holding it? Somehow, the first time that Kylo Ren met Ray, he had trouble reading her mind. To top that, she was even able to turn the power back on him and read on his emotions. Yet she had said earlier that she thought that the "Jedi" where just legend. So how was she able to use her power so readily and skillfully? Maybe she did have previous Jedi training, yet her memories where put unjnder a mental lock to protect her? What if the reason that Luke put himself in exile was not because he fled the attack of the Knights of Ren in his own name, but to protect his daughter? When the movie first starts, we find out that one of Princess Leia's former subjects was on that same planet. Maybe the child was put under his guardianship. Though it is never shown in the movie that she even knew of his presence, nor him of her's. But this is just a theory that has no base facts. Just a simple matter of connecting the dots within my imagination. Knowing the way of my luck, this is probably the furthest from the actual truth and I'm just grasping at straws.