Lots of work and kids make it so I get 30 minutes--maybe a full hour--each weeknight for either TV or gaming. As a result, haven't watched TV in well over a month. Anyhow, I've been picking through PS2 games lately so I'd like to think I'm in a similar situation.
Maximo: Army of Zin is good because the stages generally take very little time, and the entire game isn't too long. It's generally fun and easy going, especially if you like "capcom-y" platformers. I like them for the sake of the "bunches of coins" sound effect. It's like a fountain of chimes. It's really easy to pick up, play a quick stage, and go to bed. The game mechanics are fun enough--not as good as others, but still okay.
Both Katamaris are good for quick play. Most challenges are 5-10 minutes. I enjoy the Katamari very much. Me and the King of the Cosmos are very close.
A warning on X-Men Legends. I have number 2 in the series, and it's not well suited to quick play IMO. It has an assload of load times, and the goofy interface makes it so that you really have to know the game to get through things efficiently. I understand that it's a fun game, but I haven't made much of a dent in it just because I get sick of waiting on it to load.
Another one that doesn't work out as well as you'd think is Ratchet & Clank 2 (the only one I've played -- I'm getting 3 soon). Generally I like the game, but one thing I absolutely

ing hate about R&C2 is when they force me to do non-platforming stuff to progress the story. You know, stuff like star fights, rail grinding, other bullshit not involving running, jumping, and shooting the shit out of everything. Plus, once you are platforming, the stages have a tendency to go on and on. Anyhow, those little things make the game less pick-up-n-play friendly. If the stages in R&C2 were more like Maximo, where you could jump in and out without a problem, R&C2 would be the perfect pick-up-n-player: terrific gameplay, lots of fun, and easy to jump in and out of.