I second the Making connections group. You basically offer as many free books as you want to offer and set a deadline for when the review should be ready by (4-6 weeks) and while they are obliged to give a review they are by no means obliged to give a good one - that is based on the quality of your writing.
Debra's method I am considering... may kick that off tomorrow.
There are hundreds of review blogs out there and they all accept reviews. I do reviews on epublishabook.com (the fantasy, sci fi and horror bits, other reviewers handle other genres and I am not sure if we have a non fiction section or not...). I get sent many books to review (so many that I have trouble keeping up...). Do a search in the area your book is in plus 'reviews' and see what comes up.
Also, do a search on your name plus reviews... sometimes review sites may pick up your book, review it and not tell you... it happened to me, I only found it when I did a search. Was a good review too. You may have more than you thought.
Alarmed that there is a book out there promoting unethical practises...