Last month was Karen Traviss' City of Pearl
This September is Odalisque by Fiona McIntosh:
http://www.harpercollinsebooks.com/1...0/125/en/EOS10
Available as pdf/lit/prc
Can't get the .pdb version though. booksonboard and ereader don't give-away this title.
There's also pdf for Neverwhere by Neil Gaiman.