Tactics and other instructional material

testyourchess.com
Here's a site that shows great promise! Two features await you - a checkmate challenge which presents over 200 positions that have tactical forced wins. Get one right, and the next problem is harder - muff one and they get easier. How many can you get right in a row? The other feature is Test Your Move which is an online solitaire chess. It will go through the opening of an annotated game and then present you with the next position. Try your best move and see how many points it earns!

chess.emrald.net
The Chess Tactics Server. Register at the site and receive a password by email. Then you are presented with timed tactical positions to solve. It's a great idea, but the server is based in Europe, and I have just a dial up connection, and it seems that I lose a lot of points waiting for the position to appear. Or I really am poor tactically! But the positions are very good, and it's an easy way to practice a few positions a day. Just remember - at the beginning stages of your tactical journey, mastery is better than speed. So - if you don't see the answer with certainty right away - set up the position on your board and study it!

Openings