A reader emailed to inform me that there’s only a few hours left to register for LibraryThing‘s holiday book swap, which has some very simple rules: You pay $25, they assign you another participating member, then you sift through their wishlists they’ve provided and figure out some books they might like, up to $20 worth, and then you have Amazon.com ship them to that person, while somebody else is doing the same for you. (Funnily enough, I was skimming the page to see who’s participating, and I spotted one of my favorite comic book bloggers. Small world.)