Today I was sent information about this site. They promote your book free of charge, (or you can pay to get a bit more promo support). I paid. It is $10 (or $12 thanks to tax as I live in Cyprus). http://askdavid.com/free-book-promotion
I also run a promotion site for free: http://newbookblogger.blogspot.com/ . The site is very busy, and I am thrilled with the way it is growing. Several authors have contacted and said they have had a rise in sales since being showcased. I do not review the books, I simply advertise, and promote out to Twitter, Google+, and Facebook. Five per week are showcased, and I am full until October, so you can see it is getting popular! I accept all genre, and the books eventually sit on a permanent page in their selected genre for readers to find. A mini library.