If you like the Barnes & Noble classics series:
Build Your Own eBook Library - For Free
This promotion is running July 16 - September 14, so I think then new books will be uploaded every Friday or so? Here's a list of the classics available this week:
Grimm's Fairy Tales
Alice's Adventure in Wonderland and Through the Looking Glass
Call of the Wild and White Fang
Treasure Island
Adventures of Huckleberry Finn
Adventures of Tom Sawyer
Secret Garden
Peter Pan
The Wonderful Wizard of Oz
Tarzan of the Apes
Little Women
Wind In the Willows
Enjoy!