Here are some sites that I have found to be of great value:
chessopenings.com - NM Dereque Kelley explains openings very well.
The Chess Website - Excellent videos.
ChessVideos.tv - An abundant resource of top notch videos.
Exeter Chess Club coaching section - Excellent articles
ChessCafe columns (especially Dan Heisman's Novice Nook columns and Mark Dvoretsky's Instructor columns) - I can't recommend Dan Heisman enough, his videos on ICC (not free) are excellent.
50 Chess Games for Beginners - I stumbled upon this. Looks helpful, especially since the games are annotated.
Chess Visualization Training - Improve your visualization.
