Making mosaics out of broken pottery and cement. (Call the local thrift store and make them an offer on all the donated pottery that won't sell because it's chipped or cracked.)
Raising your own birdseed. (Sunflowers, millet.) You don't even have to harvest it--let the birds eat it where it stands.
Going to the public library and reading books or magazines. Sometimes they even have CDs, DVDs, and videocassettes you can check out free.
Playing cards, checkers or chess with friends (as long as you don't play for money).