So, I was very fortunate to receive a Nook this past Valentine's Day, though I think it must be noted that my husband may have just gotten tired of my "borrowing" his. Anyways, I have one now and am very much enjoying the ease of carrying around several books in one medium size portable device.
The great thing is that I don't even have to buy any books, I just download them for free from the HCPL Digital Media Catalog . Now it's true that not every book is available as a download, but there are still plenty to choose from including new releases.
If you've gotten a Nook yourself, I found that "Being Ruth"  had the best directions for downloading library books to your computer and then transferring them to your Nook. She provides step-by-step directions along with pictures (yay!) for reference. OverDrive is also testing their own "help" turtorial available from the Digital Media Catalog page.