The Book Brigade", a blog on tumblr intended for promoting books. It's follower submission based, which means you're invited to submit a post promoting your blog (so long as you're a follower. It's only fair to everyone else.) There are a few guidelines on the submission page to help you get going if you're interested in submitting your book - okay, a lot of submissions. But they're mostly for those not used to posting on tumblr.
And on another note, you're not limited to promoting just your own books! Feel free to post your favorite books, your friend's book, etc etc. So long as the submission follows the guidelines it won't get denied.
(You do need a tumblr account to submit/follow, however. But tumblr is free and pretty user friendly once you get the hang of it!)
Now it's back to editing and...ugh. Sorting out a character's backstory timeline. I hate that. A lot.