If you or your workplace have a decent-sized book collection, you might have thought of organising or cataloguing it in some way. If so, I recommend you give LibraryThing a try. It’s free (or $20 for a lifetime membership), and has lots of amazing social features, where you can see who else has your books, read and post reviews, find other books you might like—and even books that LibraryThing thinks you won’t. ProfHacker has a nice overview, and LibraryThing’s founder, Tim Spalding, gave a presentation at LIANZA 2009 which is an excellent introduction to all it can do, and food for thought for traditional librarians.