Yesterday while doing some research, I discovered that my library has ebooks that you can "check out." Some of the ebooks are through their system, and you actually check the books out -- and while you have the book checked out, you are the only one who can view it.
They also offer some ebooks through NetLibrary. I had to call my library and have them set up an account for me, but once I'm in I can search the database and access any of their ebooks. There's no limit -- I just put the ebook in my favorites list and log in whenever I want to look at it.
Although I've known for a while that my library offered the ability to check out ebooks, yesterday was the first time I had actually tried it. After a short call to the library to set up my NetLibrary account, I was able to browse the ebook and find the information I needed. Basically, I did library-quality research without ever leaving my rocker.
Ebook lending libraries are a great resource for writers (or even students, for that matter). I highly recommend contacting your library and finding out if they have a similar service.