Star Wars has been an incredible marketing tool and there's been a ton of advertising made over the years with it, but did you know they also had some of the characters make PSA's. I was only able to find a few that were real(most of them are fans making their own adaptations of what Star Wars PSA's would look like) so here they are!
Star Wars Smoking PSA
What Happens when a little droid discovers a cigarette?
You'd think an anti-smoking ad featuring Star Wars characters would feature Darth Vader (I mean it makes more sense then the droids, although I found the ad they made very endearing... especially the end when C3PO adresses the audience)
1979 - STAR WARS Drunk Driving PSA Commercial
None of the main characters are in this one... but the cantina is!
Star Wars 'Childhood Immunization' PSA
Another R2D2-C3PO combo PSA, this one talks about how important it is to have your children immunized. This PSA was released in April 1978.
These ads were all released in the late 70's, a year or 2 after the first movie was made. It gives people today an idea of the immediate impact the movie had on viewers (children and teenagers in articular) and if anything it's a shame that there haven't been any PSA's (that I know of... from an online search at least) with the Star Wars crew since. There's so much possibility! From the Emperor having a one-on-one chat with the viewer over the excesses of plastic surgery, to Admiral Ackbar smacking drugs off a kids hand while franticly yelling "ITS A TRAP!", to showing a video of Porkins telling kids to eat right and exercise in case an evil empire builds a death star and it ends up being your job to fire a proton missile through a small hole (hard AND kinky) ...
Porkins Video Tribute
So in conclusion, George Lucas, sir, please work with the government and make more PSA's. They rock, years later kids remember them, and your movie spreads some good vibes through the galaxy. It's a win-win-win. win.