Stephen Tremp, from Breakthrough Blogs, is hosting a Writers 4 Writers blog hop. This group aims to help promote members' books via twitter. It's quite simple, each month (the third Monday) a few writers will be highlighted. By visiting their blog you can pick up the promotional tweet to be retweeted. The tweet will promote the book, include a link to Amazon and ask others to retweet for you. This should help create a buzz about the book, increase sales/downloads and lift the book in Amazon's ratings. Then, when it's your turn, you'll write a tweet about your book and members will retweet it for you.
It's worth noting that this at times will require tweeting about a book you haven't read. I will in no way mislead followers to believe I'm endorsing the book, but am happy to simply send out a link and description. If a tweet sounds like a review, I'd probably reword it. For example, I wouldn't send out a tweet that read: Best mystery fiction ever! You must read DETECTIVE ZOMBIE GETS HIS MAN link.com if I hadn't read the book. I will still send out a link with a description of genre. I might add 'sounds like a fun read', or 'I'm keen to check this out'.
So if you're interested, sign up at Stephen Tremp's Breakthrough Blogs.
Remember, it's the 3rd Monday of every month!