I am a frequenter of Newgrounds. There's a lot of worthlessly violent crap you have to wade through but good stuff pops up all the time, too. These are some of my favorite things (brown paper bags!)
Warning: Newgrounds will eat your computer with pop-ups, some of them porn pop-ups. So it's not safe for work. Don't worry, though, it won't install Bonzi-Buddy without asking politely first.
CI: Unregulated - The 3-D work is amazing for flash and it manages to hold me rapt till the movie is over. I'm shameless.