Please let me know of any new resources you find and they will be added here in the future.
http://www.sudoku.org.uk/daily.asp
Daily puzzles of rotating difficulty, plus always an easy puzzle. Some discussion of strategies.
http://www.uclick.com/client/sea/sudoc/
Daily Sudoku from the Seattle Times newspaper.
http://www.scanraid.com/sudoku.htm
Daily puzzles, very thorough discussion of strategies from simple to very advanced.