I still periodically review books for Library Journal, and in with my last book they included this message:
"I need more reviewers with a strong grounding in business, able to take on a variety of books covering topics across the range of economics, whether it's exploring American capitalism, or the domestic and global impacts/causes of the Great Recession, investigating small business profiles and leadership models, or considering a biography of Warren Buffett!
If you have colleagues who may be interested in becoming a reviewer in such subject areas, please ask them to email me: Annalisa Pesek, at firstname.lastname@example.org."
Just thought I'd pass that along. You don't get paid for your reviews, but the business books aren't all that demanding, and it can be a nice credit for your skills list if you're looking for that sort of thing. Plus, sometimes you get real stinker books, but a lot of the business books I've read for LJ have been quite interesting.