For R and M,
Noted your interest in LibraryThing expressed over on False Prophecy. Anyway, if you want to play with mine a little before you make the commitment to start inputting your rather large collection, my profile is here.
I haven't progressed into actual cataloging, beyond the copy cataloging phase, but it'll give you an idea. There are definite opportunities to put your own stamp on the catalog.
I like that you have a list of the books you have, stored somewhere other than your personal computer so that if your house burns down, or whatever, you have an idea of what's been in your collection. Because, if you're me, most of your worldly goods are books. Also, the unsuggester is kind of fun, as is the part where it shows you how many other people own the same books as you. I have, apparently, so fairly obscure titles.