Here are some additional eBook resources - with a bit of a bias to SF & F. The links are annotated.
http://www.bookviewcafe.com/ Site maintained by writers - Has well know names and new writers, no DRM that I know of, and posts short stories and chapters for free on a regular basis. Several formats. Many SF & F writers, some other genres.
http://craphound.com/ Cory Doctorow - SF & F writer - publishes with Tor and other well know publishers. His site has all the books he has written available for download with a CC license. He accepts conversions from readers into other formats and hosts the files. His contracts with publishers allow him to offer the free versions. No DRM at all. There are links on site to buy copies as well.
http://www.sfwa.org/for-readers/member-fiction-online/ SFWA site - lists online fiction by SFWA members. List is growing. Has both free downloads and link to purchase books online. List can be sorted for free books. There are some Nebula award winners available for free download.
http://jiltanith.thefifthimperium.com/ Collected Driblets of Free Baen: A Frankly Promotional Endeavor - chapters of upcoming Baen books, updated regularly with additional chapters until the book is released.
http://baencd.thefifthimperium.com/ - same site - zipped CD iso files with promotional Baen books - these were released with selected hardcover editions and contain some books not in the Baen free library. He recommends you if you download any of these, mention it at the Webscription site if you make a purchase, so they stay willing to keep them available. One CD contains a fairly complete collection of all SF & F related titles from Gutenberg.org.
My Aluratek came with a list of eBook sites - but I think jlg432 hit them all in his very comprehensive list.
Many author sites have either samples or downloads on them for interested readers.
Happy reading.
I've read 13 books since I received my Aluratek at the end of May
