I volunteered at a hostpital. We had to stuff thousands of christmas cards in envelopes that would be sent to less fortunate people. I don't remember exactly how it worked, but I'm pretty sure that's what they did with them.
I also volunteered making a hockey stat site for a small league. Haha just checked it and it still works.
I did a lot of little things here and there too. We need to do 40 hours to graduate high school, but I think it's a great idea. It was not hard, the site gave me 30 hours righ there... about 1 hour per update, there was 60 games, 2 per night.