We have thousands of books in our shelves and I'd like to do some purging. Where is the best place to sell them? Ebay? Amazon? Or some other more specific book site?
Ebay will give you the best exposure but they also will take a chunk of your profits. You could try selling them on Bonanzle or Ecrater - you set up your own "store". It's free and people buy - they don't bid.