If you are interested in massively multiplayer gratuitous cartoon violence, especially if you have kids, check out
www.toontown.com. I spend quite a bit of time with my four-year-old playing (she can't read well enough to figure out some of the toon tasks), and we have a bLast. My older kids enjoy it as well, and even the old man has his toon and plays from time to time. Don't expect any major intellectual activity, but if you enjoy smacking around the evil Cogs with pies, selzer bottles, and the occasional dropped piano, check it out.
Oh, and if you see a silly looking red dog named Little Biggenfoot, that would be me.