I have the feeling that 147 is pretty pathetic for a self-professed book junkie, but I've had to cull my library extensively in the last couple of years. (It hurt.) Hopefully this is the last time, and I'm doing it right, with LibraryThing. I've entered every book and tagged it as belonging to Box A, B, C, or "Mike's house," the other place my books live for the moment.
My LibraryThing experience was pretty good, actually. I got frustrated with using Amazon as a search engine, but if it doesn't come up with your book you can enter the ISBN. And when the book doesn't have an ISBN (darn my weird books) you can go in and manually edit the information. One of my favorite features was the ability to change the cover art among options, or even upload new cover art to the site.
It's funny, I'm not particularly neurotic about organizing my books when they're out on the shelves...but I do always know where everything is by some weird visuospatial skill that only applies to things that aren't very useful. So now, thanks to LibraryThing, even when my books are in transit or in storage thousands of miles away, I can pretend I know exactly where they are.
Sometimes I get the sense I should be tutoring blind orphans instead of forming new Internet addictions.