I just recently passed my PS2 on to the kids as there is no exclusives for it I really feel the need to own. I get all multi-platform games for the XBOX. But since you have the PS2 I'll recommend a few.
Splinter Cell: Excellent stealth game. Lots of fun and the PS2 version has two exclusive levels. One of the best games made for any console IMO.
Burnout 2: Great arcade racer. Very fast racing and it has a game mode where the object is to make the biggest wreck possible. My kids love it.
Twisted Metal Black: Car combat. Pretty cool.
Splashdown: Jet ski racing. Lots of cool tracks.
Finding Nemo: Obviously good for the kids.
The Tony Hawk series: Fun for kids and adults.
Star Wars Bounty Hunter: If you are a SW fan this one is great. Creates a story of Jango Fett and his doings before Episode II. Great third person shooter.
Stuntman: Driving game where you play a stuntman and have to do different car stunts to create scenes for a movie.
Crash Nitro Kart: haven't actually played this but heard it is fun. Similar to Mario Kart for the GC.
