Was able to get a used G&W Gallery 4 on ebay for about 15 dollars including shipping a couple of weeks ago.
It's electronic old-school/new-school crack, I tell you. Old and new G&W games are on here, and they're both fun. I think there's decent replay value and challenge, because in order to open new games, you have to earn stars (non-accumulative, btw) by getting high scores above 100 points.
My favorite new school game is Chef; a little bit of Iron Chef and Emeril mixed in with Yoshi ;). The hardest game right now is the old-school Chef; it's Ed Sullivan-plate spinning craziness at its best.
Scotto, the PC version of the first GTA game had multiplayer support. I do not recall it being very enjoyable (mostly due to it being hard to run into each other and, of course, try to run each other over.