Today's top two ways to distract yourself at work are Sudokular and Shuffle. Shuffle is more fun but the Sudokular website looks fantastic.
Enjoy!

UPDATE:
Totally forgot the Simpsons wrecking ball game which comes from the fabulous Base 10 website.

SINCE THIS POST MAY NEVER BE COMPLETE I MAY AS WELL ADD ANOTHER UPDATE:
A game that I haven't tried yet but I think that it fits in well with this post - 1000 blank white cards. It's basically a game where you invent your own rules and the game can evolve over time. I think that this would be a great game for ESL teachers.

MAY AS WELL ANNOUNCE THAT I JUST LOST THE GAME:
In case you don't already know what The Game is ....
Rule 1: Everyone is playing The Game. When you find out what The Game is then becomes possible to lose The Game.
Rule 2: The goal of The Game is to forget that you are playing The Game.
Rule 3: If you remember that you are playing The Game then you have lost The Game and must tell everyone.

A while ago I put a link a page up about The Game on the Bedlam Wiki but the whole site appears to be dead now. Pity. But brilliantly I just found out that there is a website devoted to The Game as well as a Tshirt printed with the rules! Now you too are playing the game - all you have to do is forget. Enjoy!