Via As Above, I find the wonderful Low-Tech Game Systems.

This article lists loads of games you can play with voices, hands, pens, paper, and coins. You need never be bored on a train again!

From this excellent starting point, I discovered (or rediscovered) some fabulous gaming related places:

• Critical Miss, the funniest gaming site on the net. Particularly good: Nuke The Crap Out Of Europe, Pimp: The Free Collectible Card Game, Gaming With Nothing, The RPG Cliche List, and, oh, most of the rest of them.
• The Window - an RPG for grown ups.
• Cheapass Games, including Fight!
  
• The World of Abstract Games
• Game Systems, Card Game Systems and Board Game Systems, other articles in the same series, are also worth a look.