It depends upon what you have in your personal library, I think. If you have mostly classics and romances you wouldn't have much in the way of resale value, not unless you have an old Judy Cuevas or something people are dying to get their hands on again.
If you know your particular likes in reading then you might be able to resell them again on the likes of Amazon Marketplace or ebay or something like that -- but then you'll have to deal with postage issues when people do buy them. On the other hand, this does mean that you'll be able to pad out your future ebook buying kitty.
e.g. at one point, many years ago, I used to go hit the library sales and pick up all the really old SF stuff which, yes, I did make some money on when I sold it years later. A box of books for $1! People do want old things
