I picked up some information on ACCESS Blood Bank today (with offices on Lake City Way and in Redmond) about dog/cat blood donations. Since I cannot donate blood myself (stupid federal regulation enacted in 1998 prevents me from donating because *gasp* I might have mad cow disease) I think this is a worthy cause and plan to make appointments to take my dog and both cats down for screenings.
Many clinics keep clinic cats as blood donors. They are actually a very important part of the staff. It is a little harder to have a clinic dog:-) In exchange for food and board they give blood when needed (usually a couple times a year). Beverly at Lien Animal Clinic (also known as Mrs. B) is prized for her rarer type B blood.
One of my cats that survived Panleuk had received a blood transfusion from Flower–a Lien Animal Clinic cat. So, in an emergency situation, he donated blood to another kitty that was in serious condition as a thank you to Flower!