Any OpenLibrary.org account holder can borrow up to 5 eBooks at a time, for up to 2 weeks.
-Internet Archive Forums
If you want access to 80,000+ books for the price of logging on to a website, Open Library is the place for you. The Internet Archive and a few forward-thinking libraries have teamed up to create a virtual lending library. This is great news for everyone, but a particular boon for researchers. One more cut and paste quote, "Genealogists are some of our most enthusiastic users, and the Boston Public Library holds some genealogy books that exist nowhere else,” said Amy E. Ryan, President of the Boston Public Library. "This lending system allows our users to search for names in these books for the first time, and allows us to efficiently lend some of these books to visitors at distant libraries."
Here's the full press release. I suggest you bookmark Open Library and start borrowing.