I don't have a lot of money to give, but I have some and I like to volunteer when I can. I've donated to the Crohn's and Colitis Foundation, because that personally affects me. I have donated blood to the Red Cross (even though until recently I was not supposed to be allowed to, shhhh...) and am registered as a bone marrow donor. I've volunteered at auctions, walks, and other events held by the MS Society, which I got involved in because my aunt has it. I've volunteered at the local humane society. I've also volunteered at the local food pantry, and a really cool pay-what-you-can restaurant downtown. And recently an LGBT center opened in my hometown, so I've worked at the desk there some.
When I was a church-going lad, we would go down to Kentucky to work with this charity called Mountain Outreach, pretty similar to Habitat for Humanity, just building homes for folks. I learned a lot about carpentry and electrics there. And then I've volunteered with Habitat some, but they are a bit less hands-on at their job sites.
I once went on a sort of "voluntourism" trip to Jamaica through my school that I'm not 100% proud of now. We walked supplies into a rural village, helped add a wing onto someone's house, and hung out at nursing homes (which in Jamaica are mainly for people with mental disabilities who are homeless). I still consider it a great personal experience but in retrospect I now know why those types of trips can actually be counterproductive to charity work in other countries.
One charity I'd like to get involved in someday that I only recently discovered is the Kevin Spacey Foundation, which has a goal of bringing creative arts to communities where children normally wouldn't have the opportunity to learn about it.