Luke Sykwalker — Neutral Good. You could maybe argue that Luke was Lawful Good, but in the movies, he doesn't seem as concerned with rules and regulations as he does with just doing what is right. As shown in the Empire Strike's Back, he's willing to go against more 'wise' (Lawful and Logical) counsel in order to help his friends. Even though Yoda deems him 'reckless', his impulsive nature seems to stem from his dedication to those friends and the Rebellion, rather than selfishness and personal pride. He is lead by his heart and not his head—and in Luke's case, this is a good thing, because he has a good heart. I think it is this that kind of sets him apart from the other Jedi, who were Lawful Good (see below).
Leia Organa — Neutral Good (with Lawful tendencies). She was a Senator. She eventually becomes the Chancellor. So yeah, she knows and believes in the just application of Law. But in her own rebel activities, she's proven that she will go outside the bounds of Law when she has to.
Han Solo — Chaotic Good (with Neutral tendencies). He's impulsive, brash and cocky. He's a risk-taker and prefers working alone and outside of anyone else's control. He'd have you believe he was a mercenary at heart (his Neutral tendencies), but everyone knows that just isn't true.
Anakin Skywalker — Neutral Good (turning to Neutral Evil). Like Luke, Anakin began as a person with a good heart. He honestly wanted to help people. He connected with others—and with his job as a Jedi—on a personal level, rather than professional. Rules didn't matter, doing good did. As he begins his transition to Darth Vader, Anakin's Neutral outlook turns more and more inward. He becomes concerned more with himself and his personal needs than with the 'big picture' going on around him. He becomes too proud of his own abilities and too frightened of personal loss to function within the Jedi, and this makes him a perfect candidate for recruitment by the Sith. It is his own selfishness that brings him down and that drives him on as Darth Vader. Some might argue that Vader (as a symbol of the Empire) is Lawful Evil, but much like the Emperor, it seems that his quest for 'Order' is selfish at its core. He wants to control things so that HE will not get hurt again, so that things will go as he wishes. It isn't Law he is interested in, it is his own will, and that is quite selfish.
Chewbacca — Neutral Good (with Chaotic tendencies). He cares about his friends and family and will do whatever he can to protect them, in or outside the law. Where the Chaotic aspect of his personality comes in is his almost berserker like anger.
The Jedi — Lawful Good (with Neutral tendencies). Bound by strict rules, philosophies and customs, the Jedi are peacekeepers and enforcers of the Law. In the Old Republic, they seemed to be very much rigid, to the point where their customs seemed to be more important to many than just doing good (witness Qui-Gon and the Jedi Order simply avoiding the issue of slavery in Hutt-Space because it was 'outside their jurisdiction). Still, there were some who were willing to bend these rules in order to get the job done (witness Ben Kenobi and Anakin Skywalker and their 'aggressive negotiations').
The Sith — Neutral Evil (with Chaotic tendencies). The core of Sith philosophy seems to be self-aggrandizement. You climb to the top over the bodies of your adversaries and 'allies' and once you're there, you do everything you can to keep everyone else 'in their place'. However Lawfully ordered Palpatine's Empire was, it seems only to have been so because it was easier to control that way, not because Palpatine particuarly wanted law and order. Among their own, the Sith are cruel and pragmatic, viewing nobody as a 'friend' and always looking for signs of weakness in their superiors in order to take them down and assume their place. This is really where the Chaotic tendency seems to come into play. With all this backstabbing, it would be incredibly difficult to keep a large number of Sith together for any length of time.
The Empire — Lawful Evil. The Empire is pretty much the epitome of Lawful Evil. Order is all important, and any means to that end are acceptable, no matter how cruel. Officers work within the framework of the system. Yes, they jockey for position and even backstab each other, but always within the 'rules' and always with the thought of climbing higher in the hierarchy. Even rivals will usually work together (at least until one gains the upper hand).
Other than just being an interesting mental exercise for myself, this whole issue of Alignment (and reading some Star Wars Sourcebooks about other Force traditions) got me thinking about the Krath. They were introduced in the Tales of the Jedi comics, set some 4,000 years prior to Star Wars: ANH. The Krath were an order of evil, warlike Force users who made a bid for galactic supremacy. At first, I wasn't too keen on them, as they didn't really seem to be much different than the Sith. But in working all this out in my head, I saw a way where the Krath COULD be different, and in an interesting way.
Picture a group of dark-side Force users who didn't have the chaotic and self-centered philosophy of the Sith. Imagine instead that they followed the Lawful Evil track of the Empire. An organized and cooperative group of bad guys is always more threatening than a disorganized and factionalized one. I could see a new Krath Order rising in the wake of the civil war and the Nagai invasion in my own campaign. Based again in the systems of the inner core of the galaxy (where Palpatine's clone had been reborn in the Dark Empire series), the Krath could expand, learning from the downfall of the Sith—and from ancient records of the Krath themselves. A new culture could be born, with Force users as its aristocracy—the 'superior beings' in a culture centered around servitude to them.
The Krath could train their own Force elite and even try to entice members of the Jedi and Sith into their ranks by playing up to the tendencies of both groups. The Jedi may begin to feel 'under appreciated' and disgruntled in their roles as selfless Galactic guardians. The younger ones especially could be tempted by offers of wealth, power, respect and privilege. Some of the Sith may not like the self-defeating nature of their own order, with its chaos and backstabbing and general disorganization. Those Sith with any 'sense of honor' might find the Krath more to their liking—and needless to say, for evil and selfish people, power and prestige are big draws.
Yes, it all gets me thinking about whether the Krath ought to make a reappearance after 4,000 years.