Bricksinmotion: http://www.bricksinmotion.com/ An entire brickfilming community with forums, a film directory, and a yearly contest.
Brickfilms: http://www.brickfilms.com/ Another brickfilming community with forums, and a film directory, and has just been re-launched since it died years ago.
The Brickfilmers Guild: http://brickfilmersguild.com/elgg/ A site for brickfilmers to socialize. Create a profile, join some groups, add your videos to the site, and chat with other brickfilmers from around the world!
Brick Film School: http://brickfilmschool.com/ A site with lots of tutorials on how to make brickfilms.
BrickFlix: http://brickflix.org/ A brickfilm festival.
MOC Pages: http://www.mocpages.com/ A place to show off your lego creations!