LibraryThing is a site where people can catalogue their books. It has many connective and informative things going on now, too, including good local info.
I have three collections there:
my main one, (which has a selection of my faves)
my inspiration-audiobooks one,
and my gardening books one.
The widgets for two of them are in the sidebar, here, too.
And of course, the gardening books widget is in My Lovely Garden blog sidebar.
I so enjoy the book-cover artistry made visible in the 'covers only' view of my books there.