I wrote a post about the BookChaser Editions service last year, but encountered a reference to another service they offer, and this led me to others:
- BookChaser Covers : compares cover images available from Amazon, Google Books, LibraryThing, and Open Library.
- BookChaser BookInfo : compares information about a book obtained from Amazon, Google Books, ISBNDB, Library of Congress, LibraryThing, Open Library, and WorldCat.
- ISBN Analysis Tool : compares x-ISBN-like service availability for a given ISBN obtained from Amazon, Google Books, LibraryThing and WorldCat.
All lookup services are by ISBN.