USER COMMENTS:

Why not just do a Google search instead of looking here?  This is more direct, indexes collections specifically, and won't throw out red herrings. 
Memphis Univ School Library

"...an astonishing number of electronic books...from an equally astonishing number of sources ... impressive. Very impressive..."
Lindsay Periera, REDIFF.COM (INDIA) Pick of the Weekend

"One major area of difficulty in the electronic book area of publishing has been bibliographic control. Libraries do not include, in many cases, free resources on the web as cataloged records in library OPACs... A very useful resource in this area for libraries and for end users of electronic books."
David Dillard, TEMPLE UNIV.

This is a big improvement over the sites I've been recommending to students. I especially like the clarity of specifying just how much particular documents will cost to download [when there is a charge]...overall, a most useful reference. Thanks very much...
Jonathan Betz-Zall, Branch Librarian, CITY UNIV., Everett, WA