I wish I could accept books to sign and return — I used to, but came to the realization I was spending 4-5 hours a day dealing with snail mail requests and signed books, and that it was actually starting to prevent me from writing. So I made an arrangement with Book Moon Books, an independent bookstore run by Kelly Link and Gavin Grant — I make sure they always have signed copies of my books on hand, and you can order any or all of the books by calling the store or ordering online. They have signed hardbacks, paperbacks, box sets, etc, and will ship anywhere within the U.S.
I do get requests for “autographs” sometimes, but autographs aren’t really something writers do. That’s why signed books are meant to be something special. Scrawling a signature on a piece of paper feels silly in a “Why would anyone want that?” way, and again, it’s a matter of time and the cost of postage, both of which prohibit me from being able to send out signatures. (Again, signed bookplates are only available to schools and charities — not to individuals.)