Library Thing is a pretty neat tool, especially if you pony up for the full or lifetime membership so that you can enter more than 200 titles.
It could be especially cool if you access it from mobile phone - http://www.librarything.com/wiki/index.php/LT_Mobile - no more buying/ checking out a copy of a book that you have at home waiting to be read!
And did you see that you can keep tabs on local bookstore's prices and availability of your books? http://www.librarything.com/wiki/index.php/Bookstore_integration
How about getting a :CueCat scanner so that you can add books quickly to your LibraryThing list by scanning their ISBNs? http://www.librarything.com/wiki/index.php/CueCat:_Using_with_LibraryThing
No, I didn't check out any groups, nor recommendations from others - I have such a backlog of books that I already need to read for school and want to read for me that I surely don't need to add to the enormous mentally-held list of "next I will read this and this and this book." Sure to be a neat feature for those who do want some guidance on what to read next.
But I do plan to add my school library to LibraryThing, if possible, even though we don't currently have online collection searching capabilities (yes, we are working on it, but money talks, eh?).