The folks at RatherGood.com have no end of Flash animations to entertain and delight. May I suggest starting off with Moon Song, and Biscuits?
Along those lines, I also found (the far too obviously named) Flash archive with even more great goodies. Yes, you’ve seen some of these before, but there are some new ones there too. And, of course, regular laughs can be had at HomeStarRunner.com, where Strong Bad’s Email (updated each Monday, usually) will likely make you a repeat visitor.