If you're on LibraryThing, feel free to drop by and see how many books we have in common.
LT has this new 'also on' connection feature. If you add all your blog links to your profile it can scan your friends & contacts and tell you which of them are on LT. (LJ friends are supported.)
If you're not on LibraryThing, it's a pretty neat way to catalogue all your books. You can add up to 200 for nothing, and after that there's an annual or lifetime membership for a fairly decent price.
Authors: you might like to set up a profile, add your own titles and notify LibraryThing so they add the coveted yellow 'LT Author' badge. When your novels show up on someone's list, if they click your name they'll be able to see your profile page where you've (hopefully) listed links to your website, blog and so on.
Simon Haynes is the author of the Hal Spacejock and Hal Junior series (Amazon / Smashwords / other formats)