He's not a local guy but he writes about the Mariners at USSM as I'm sure many of you know. They're not a part of SBN but I know John reads them and they have a very close relationship with Lookout Landing. Please read this blog and honor his request to donate blood if you can. From the comments on Shannon Drayer's blog I also learned that he'll almost certainly need a bone marrow transplant or some sort of stem cell treatment. The comment also asked that anyone who donates blood be HLA typed to see if they are a match. That's kind of a good thing to do in general, not just specifically for this particular case.
I've learned a lot from the USSM guys over the years...from way back in the usenet days. I haven't read the comments in the blog I linked to yet so there may be many other potential ways to help should you wish to do so.