Widescreen rocks when it comes to movies. Anyone who thinks the laughingly named "full screen" is the way to go with
movies needs to be locked in a room until they know better.
Widescreen gaming is taking a little longer to take off, though. Having recently gotten a widescreen laptop, I eagerly installed games, figuring most would support widescreen. Nope. Squish-o-vision ahoy. Rise of Nations? NADA. Neverwinter Nights? No dice. Raven Shield? Not a chance. Doom 3? Guess.
Having done some digging, I came upon Tiger Dave's website, dedicated to widescreen gaming, with a list of games, old(ish) and new, with details on how to convince them to play nice on screens with a 16:9 aspect ratio. If it's popular, it's probably listed.
One caveat: Sadly, if you want to view the screenshots of games running in all their widescreen glory, you've got to cough up some cash.