A social-media-styled Goodreads for kids! Create a bookshelf that students can take from and make their own bookshelves. Post about books you've finished, books you loved, and more. 

LibraryThing is an easy-to-use collection-building website. LibraryThing for Circulation lets you circulate your classroom library by keeping track of who "checked out" which book. 

Livebinder lets you create a "binder" of information to keep all in once place. You can embed a LibraryThing widget in one of your pages to act as a browsable collection.