ISBN.nu is a website that allows you to search a vast titles database
(of mostly U.S. in-print and out-of-print titles)
using title words, author's name, subject, any combination of those three, or ISBN.
It is owned by freelance journalist Glenn Fleishman
and began its life as a "proof of concept" project. Its database is created from information licensed from the Informata division of Baker & Taylor and now comprises over 3 million entries.
When queried on a particular book, the site presents the prices, availability, and shipping time of about a dozen online bookstores. The site makes its revenues through commissions when books are purchased through links to those stores.