My SO and I just got back from donating blood, and once again it was a somewhat disheartening experience. The donation itself was fine; what was disheartening was the lack of other people donating blood. We were the only people in the donation center for about half the time, and for the entire time the place was less than a third full. After finishing up my blood donation, my phlebotomist was just wandering around the donating area, obviously quite bored (she reported that it was "really slow" today).
There's certainly a need for blood right now (there always is!), as the Southern California Red Cross reports that they have only a 1-day supply of O-.
So, if you haven't given blood in the last 56 days, and haven't been officially informed by your doctor or a blood-donating agency that you cannot donate blood, go schedule an appointment at the Red Cross's Give Life website (or whatever your local blood donation agency's website is) and go donate. At the worst they'll tell you that you can't donate, and at the best you'll walk out about a pound lighter than when you walked in.