Bubblebox is a great site where you can try out new internet games.  The one I am really into right now is called Block Drop it seems deceptively simple but it does not take you long to realize that it is a puzzle game that requires you to think many moves ahead.  I have spent a lot of time with this game it is addicting to say the least!  If you get the chance you should give it a try.  It keeps track of your levels and high scores so you not only compete against the computer you compete against yourself as well