John K's Jetsons, Cartoon Research and Animation Blast
While watching John Kricfalusi's version of the Jetsons on Cartoon Network (very twisted), I noticed a listing of 'Flash Animators' in the credits and decided to do a name search and found a couple of great and huge animation sites.
Cartoon Research is put together by Jerry Beck, author of Looney Tunes and Merrie Melodies : A Complete Illustrated Guide to the Warner Bros. Cartoons. The site is packed with fascinating cartoon history and current animation news.
Animation Blast is a blog-style magazine site with some good insider info and great interviews. Caution: be prepared to get out the Visine and spend countless hours delving into these sites.