I find ereaders intriguing (especially the Amazon Kindle and the Barnes & Noble NOOK), but I've noticed that the price of the average ebook is almost the same as a dead tree book. Why should I plop down money for ebooks that are in the public domain? Consider the H.G. Wells 1898 classic The War of the Worlds: Some retailers want 95 cents for their edition, which isn't a lot of money, but times are hard (I know... I recently went through a wee bout of unemployment); so I went looking for a free edition of War of the Worlds, and I discovered thousands of free ebooks are available for science-fiction and fantasy fans.
Amazon.com offers close to 40,000 free science fiction and fantasy ebooks available for download on the Kindle. In comparison, I only found 710 free sci-fi and fantasy ebooks available for the Barnes & Noble NOOK. (I realize there are many more ereaders on the market and a number of tablet computers that allow you to read ebooks, with features like Wi-Fi access and the ability to play MP3s; unfortunately, all of those devices are out of my price range.)
A great resource for free ebooks is Project Gutenberg. Yes, Project Gutenberg still has the text and HTML files that you either love or hate, as well as books in both EPUB and Mobipocket formats. Project Gutenberg features older works (that's almost required to be in the public domain) such as The War of the Worlds, though there are a number of authors who might be of interest to fans of Wells. There's works by H. Beam Piper, including the classic Little Fuzzy, a tale as fresh today as when it was first published. You'll also find listings for Marion Zimmer Bradley, who is one of the authors responsible for me losing a lot of sleep. If you'd rather search the Project Gutenberg "shelves" yourself, you can always query science fiction or fantasy to see what interests you.
Project Gutenberg even offers free audiobooks, though the selection at LibriVox is much larger. The quality of the LibriVox readers' varies a lot. I don't mean that to be a slight against the readers (they are all unpaid volunteers after all) -- it's just that I never imagined the John Carter of the House of Helium had a German accent. Podiobooks is another site I check for free science fiction and fantasy audiobooks. The books on Podiobooks aren't older books -- in fact, some of the titles haven't even been printed yet.
My biggest problem with listening to free audiobooks is that sometimes I like the book so much that end up going out and buying the print version. My guess is it's a conspiracy involving Christiana Ellis, Scott Sigler, Mercedes Lackey, J. C. Hutchins, Phil Rossi, Cory Doctorow, Mur Lafferty, Steve Libbey, and Philippa Ballantine. In fact, I'm buying more books than I have in years, and I'm quickly running out of places to keep them -- that's why I'm serious thinking about getting an Amazon Kindle. I've weighed the options, and a Kindle is cheaper than a bigger house.