If you've got no buddies to play chess against then this is your answer - with up to 256 players allowed to play at any one time and lots of exciting and fun formats, you really can't go wrong in terms of opponents that meet your level and something a bit different.
The game is based on the KI Chess Engine which is powerful enough to allow you play against several players at once or in teams. There are several different formats available such as Bughouse, Quad (four players on one board, Roleplay chess, Darkchess (only accessible squares are visible), Turquoisechess (No check, no mate) and even Atomic chess (Pieces explode when capturing). There's also the rather bizarre Cylindric Chess (like playing in a tube)and Shuffle Chess (pieces are placed randomly on the baseline). In addition to all these fun features, the game also gives you control over the size of the board, and even the number of pieces on the table. You can also chat to opponent while you play although the problem seems to be that there isn't always a great deal of people online to play but maybe as it gets more popular, this will change.
This is a fun variation on the chess genre and also a superb option for those that want to play team chess across the internet.