This is my favorite place to play on the web!!free chess,24hrs a day,free grafical interface like i said great site www.chess.net/

Here is another good chess server totally free !many interfaces to choose from,XBOARD,CCLIENT and morewww.freechess.org

This is the most popular chess server on the net! but you can only play free for 7 days then its 50 $ a year.Internet Chess Club

This is the home of the United States Chess Federation.A membership will let you play in over the board tournament all over the U.S..They also have the best chess magazine that i have found and articles from GM's ,list of local and national tournaments.U.S.C.F