TolkienBooks.net is the home of An Illustrated Tolkien Bibliography.The website aims to list all British editions of the published writings of John Ronald Reuel Tolkien (author of The Hobbit and The Lord of the Rings) and to illustrate changes to the texts and covers.
You are privy to a lot of information regarding editions, what the print run numbers were and much, much more. My favorite pages are from the Articles section. Here you can find the contents and more information regarding all Tolkien's Middle-earth titles and a few scholarly titles too.
This site is very easy to navigate and is kept up to date with new collectors information.