Recently, I got really inspired by an advertisement on the television. It is related to blood donation. I am not here to reiterate it's importance. Everyone understands it. You can donate blood in blood donation camps organized by some clubs and associations. However, live blood donation is probably more satisfying. I am yet to get such a noble opportunity (probably, my blood group is so common).
I found few websites which work on this (live blood donation). You can get registered there and become a blood donor. They will inform you whenever blood (of your group) is required.