Free book site

So I signed up for this free promo site. They promise to send my book to readers who sign up on their site. No money involved, but it's a way to reach new readers and build a bigger audience for my work.

What do you think of this? Would you sign up for a site that promises to email you a free book every week? Do free books make you a little leery?

I guess my real question is, "Will this work for me as an author as a way to promote my books and get more readers which will translate into more sales?"

What questions do you ask about free book sites?

Here's the link to Book Breeze. Check it out and see what you think. Then let me know. And in the meantime, enjoy some free books for your ereaders.