There used to be site at the address
www.mslit.com. It was owned by Microsoft and used to support Microsoft Reader ebook format. The site wasn't very pretty, but it had an excellent search function that covered all ebooks in MSReader format.
The ugly but functional site is gone. Sometime in the last two weeks Microsoft started redirecting the URL to
www.microsoft.com/reader. It looks like Microsoft has noticed the growing ebook market, and has decided to take it seriously.