THWACK! has challenges as well as being an awards site and a general silliness site. Run by my good friend Fruitcake. I make the graphic awards.
 

Leprechauns Made Me Do It! is a site that is dedicated to leprechaun fiches. It's the only, and largest, lep fic archive on the 'net. Check it out. It also has challenges.
 

World's End awards site. This place is really cool. I should know, I make the graphics for it. Plus Judgment is really cool.