11 Second Club
Monthly character animation competition using a set dialog from a movie. Public critique and voting.
http://www.11secondclub.com/

Animation Club
Melbourne,Australia, competition to animate a response to a given topic, with monthly screening of entries.
http://www.rapidfirecomedy.com/animationclub/

ANIMAX Awards
Annual pan-Asia animation script/story competition. Winning entries are professionally animated and screened on ANIMAX.
http://www.animaxawards.com

CGSociety - Challenges
Quarterly online computer art competition based on set themes. Closed judging, multiple awards in different categories, software and hardware prizes.
http://features.cgsociety.org/challenge/

Minimotion Competition
Information and entry form for the annual 10 seconds animation competition. A jury will review the works and award the best animations with prizes.
http://www.minimotion.ch