First off, thanks to my friend Watty who hipped me to this.
From May, 5 to May, 19, the National Marrow Donor Program is having a awareness and recruitment campaign. The first 46,000 people who join the registry including 10,000 who join online (you will be sent a kit in the mail) can do so for free. Usually there is a fee for joining the registry. The website has information on joining, the need for registered bone marrow donors, and FAQs. The Austin and Round Rock locations (see the link to the right) are also participating in this drive.
I joined the registry years ago. I happened to be at the center to donate blood when they told me that if I did aperethesis (I doubt that's spelled correctly), I could join the registry without having to pay the fee so I did. I've never been contacted but I certainly could be in the next 21 years.
If it appeals to you and you wish to be on the registry, please take this opportunity to join.