Sure you want!
A really good source for free games is Gametap.com. They offer 40 games for free including recent games like "Tomb Raider Legend", "Colin McRae Rally 2005" and "Second Sight". And they also provide us with classic games like Metal Slug, Ghost'n'Goblins and my favorite of the past: Cannon Fodder.
Now you are curious, right? So how do you get these games?
Just download the free gametap player and start picking up your favorite games.
The whole service is based on advertisement. So while the games are loading you have to watch an ad, that's all.
So it's not completely free - but almost!