One good place would be a forum, contact the moderators or admin and ask them how can they help you get reviewers for your product. In some forums you'll have to buy Ad space and on some forums they'll simply tell you to post it on a specific section.
Bloggers are also a great way to find reviewers, you can give them a sample of your product or the whole product in exchange for a blog post review. Other blogs have a dedicated section for product reviews, you can negotiate an affiliate/JV deal or purchase a sponsored review.
Hope that helps.