They have a very long and extensive list of volunteer reviewers that you can contact, and some of those will even review electronic copies of your book. (thebookdesigner.com)
Many of these sites rely on volunteer reviewers who are allowed to choose the books that appear interesting them to review; the rest of the titles fall by the wayside. (publishingperspectives.com)
I desperately need more volunteer reviewers though — so if you fancy reading some historical fiction please e-mail me! (authordebbieyoung.com)