Peer ratings on book reviews- suggestions needed

Hi,
We have 4 member teams for each book club and I need them to rate each other's book reviews. Is there a site where this can be done ? I tried using irubrics but it was not very intutive. I am wondering if I should have each group create a blog or wiki but no sure if there is a an 'amazon' style rating system that can be created for the readers. Any help will be great !
Thanks