Social Sites for Readers

I have an amendment to my previous post, about the ways in which reading-related social sites are used.  I wasn't sure, at the time, if users of these sites could distinguish between different shelves -- for example, if they could designate a shelf for items "to be read". (The single most useful shelf for anyone using social bookmarking tools to "Add this Book" to a social site.)

I've joined all three communities -- Shelfari, LibraryThing and GoodReads.  (Click on any of those links to add The Post Pub to your friends list.)

As far as I can tell, GoodReads is the easiest of the three in which to separate out lists and designate items To Be Read.

More on the strengths & weaknesses of each site soon...