I often donate money, although don't have any direct debits atm. Around Christmas, I tend to buy a lot of presents from various charity shops, and will get a few people oxfam unwrapped. I'm pretty sure where i'm from i've never seen much extra charity stuff around Christmas, will have to look though. Buy the Big Issue regularly too (although i've not seen one in Leeds for AGES)
I was in America with my family once, think it was around thanksgiving and in the supermarket they had an option where as you bought your groceries, you could also buy a (I think $10) food hamper which would go to the homeless, they had them already packed etc. so people could see what they were giving, seemed like a pretty good idea. I'm sure if something like that was available here, loads of people would do it.