I do, but only if they are doing something. There is an old guy here who sits on a corner regularly and picks his guitar. He is not a good guitar player, but he's trying to do something! I always throw a couple bucks in his cup.

When I lived in Calgary, there was a newspaper that homeless people could sell. Instead of asking for money, you could buy a paper for whatever amount you felt like giving. I had a favorite young man I always bought mine from. Depending on my own financial situation at the time, I often overpaid alot for that paper!