NetGalley is a website where librarians, teachers, bloggers, book reviewers -- basically anyone who reads and shares those books with other readers -- can get free downloadable advanced reader copies.
This is a valuable tool, especially for librarians, for several reasons. First, it's a great help as a selection tool, so you know what's coming out and how good of a read it is. Second, print ARC's can be a pain in the ass. Yes, it's awesome to get them in the mail directly from the publisher. But you can't put them in the collection afterwards and you can't have the Friends of the Library sell them. I give them away to the kids in the Teen Zone, which is cool, but sometimes the ARC can differ significantly from the final work, and that kid may never pick up the final copy.
So NetGalley fits a much needed niche. By having the ebook available for a limited time (usually 60 days), I can read an advanced reading copy and then have it go *poof* from my ereader after that. I think it's a lot more earth-friendly than printing a bunch of ARC's.
If you're a librarian, it's super-easy to sign up and get approved. Just make sure to include that you're a librarian in your bio, and if you're a ALA member, include your membership number and you're pretty much automatically approved.
If you're a blogger, it may be a little harder to get approved, but it's certainly worth it to try. If you're not a blogger, but have thinking about starting a blog to review books, maybe this will motivate you to start one!