Author John Passarella and his wife Andrea run a charity fundraiser called Matthew's Miles to raise money for the Children's Cancer Foundation. Although the primary purpose is a walkathon, there is a set of affiliated eBay auctions associated with it, with all proceeds going to the CCF. There's a lot of nifty stuff there, including signed Buffy and Angel books by various cast members (and even a Serenity comic signed by Joss). There's even a frickin' huge pile of Laurel K Hamilton stuff. All donations are tax-deductible, as well.