Ocelot took my answer! Side walk chalk and big dry erase board.

Also author Peggy Kaye has a series of books called Games for Math, Games for Reading, etc.

You may not find every game useful as written (they are k-3rd grade level) but I found by reading them I could adapt them to a topic we were studying. It also made me realize that you could turn anything into a game with a little thought. Soon my son was making up games and game boards too.