Super Smash Flash series sorta. (until I downloaded them)
I don't really play much. But like everyone else in this thread I used to play a lot.
Snowy the Bear was the shiiiiit dawg. He was pretty much the mascot of browser games to me.
Tag Team Titans is also one of the best broswer games ever.
I played a lot of the Cartoon Network stuff and I remember some of the songs like Courage's Creep TV and Dexter's When Stuffed Animals Attack.