Check out SignedPage.com.

This website sells first editions of books signed by the authors for fans who can't make it to book signings or whose cities will not be visited by authors on their book-signing and publicity tours.

Notables on the site at this time are Jim Butcher, author of the Dresden Files, who will be offering signed copies of his latest book, White Knight, and Jacqueline Carey, whose latest novel, Kushiel's Justice, will be released on 20 June 2007.