OK, so you're not a Star Trek fan. If you're more likely to be swinging a light saber in your imagination -- and you've been envying iPhone owners their game called Star Wars: The Force Unleashed -- then here's something to keep you busy: The Schwartz Unsheathed. (Don't know about The Schwartz? It's part of Mel Brooks' satire on sci-fi movies, called Spaceballs.)
Basically, what you get is a light saber (of any color you want) against a background of stars that emits that characteristic electronic hum. Wave your smartphone around, and you get the "whoosh" sound from the movie, along with an occasional "crack!" that indicates you've made (virtual) contact with somebody else's light saber. You can even have heroic background music that plays as loudly or softly as you want (or you can mute it completely).
What does this have to do with Spaceballs? Not a thing, really. But by avoiding any mention of that S**r W**s film, perhaps the creator of this clever little app won't have Lucasfilm's lawyers to duel with.