I wouldn't recommend Red Cross. Few people I know who worked with it say it's a majorly scammy rip-off. Way too high overhead expenses.

FYI, this past semester in one of my classes we had group projects where we had to organize some sort of a group to manage a project of our choosing. One of our class groups organized a bar crawl for charity (people go bar to bar around down town, and part of the proceeds, plus whatever is donated or earned from selling raffle tickets, goes to the charity). That group's first charity of choice was St. Jude's, since they have a major research hospital right here in our city. St. Jude turned them down, because they wanted to know where donations were coming from, and they did not want to be associated with money coming from alcohol sales. In short, St. Jude is not short on funds, and is very very picky. With Bitcoin having such shady publicity, I wouldn't hold your breath. Sorry. Still, at least it's a good practice run.