There are a bunch of other bloodtypes besides A, B, AB, and O. Very rare ones that are like a fraction of a percent of the population -
site I found via Google.
I am O positve and am reaching the four gallon mark. However, the place I go to doesn't like me doing whole blood and rather I donate platlets. Which, is a somewhat more tedious procedure. It involves a needle in each arm with one hand pumping blood, it going into a centrifuge to take out the platelets and everything else is pumped back into your other hand. Even though they like my platelets (I have another factor in my blood which is uncommon) my count is low so it usually takes me around an hour and half to two hours to complete the donation.
But, it's all good they use them primarily for people with cancer and unless I am called in for a specific patient (which happens time to time) I have mine sent to the local children's hospital.
Also I got myself onto the national bone marrow list and I suggest everybody do that.