If you don't mind reading on a computer and don't mind downloading the sony software, you can try the free books on your computer. I've been enjoying the free give aways by Harper Collins.
http://www.harpercollinsebooks.com/e...CIP_EOS_051508
However, their giveaways are often fantasy/sci-fi but I think it's a great idea.
I really wonder if the give aways have had any positive impact on the sales of the rest of the series or even other titles by that author. I'm guessing that's the goal and I wish I knew if it's working.