I'm trying out LibraryThing to catalog my home books. 200 books are free, then it's $10 a year (or $25 lifetime).
I'm hooked on this now. I've entered dozens of books in less than a half-hour, just sitting in my book room looking at the shelves. You barely have to type the title (and sometimes the author, if the title is common) and it finds most books. You can quickly add tags (categories) so you can search your library quickly in the ways that work best for you, and you can give your books ratings. I love, love, love this.
I've added a widget to the right margin of PCJM that should give you a sampling of book covers from my collection (well, of the books entered so far -- we will never enter ALL our books, I'm sure...just too many). I believe that if you click on any of the covers and are delighted enough that you want to buy a copy of one of the books yourself, I get the tiniest cut from my Amazon Associates account. Like, a penny, or something. Go nuts!
You'll note that I was even bluntly (stupidly?) honest, entering books I perhaps should be embarrassed to own, like "Real World" roundups. Um, yeah. When I get around to giving those to Goodwill, I'll take them off the list, but for now, it's an honest rendition of a part of our library.
I should note that an acquaintance, Wil Shipley, has a business, Delicious Monster, which sells software that does this kind of thing, and it also gets rave reviews. It's for Macs though.