I really like the idea of using something similar to the stack overflow model to help with peer review. It could open up the peer review process to more people for a longer period of time, giving a higher chance that more people will contribute if there is interest and a higher overall quality of discussion. All contributions give you a clear increase in reputation points.

Groups of academics could band together to form online-only journals on a specific topic and then allocate medals to papers that are considered accepted. So while there may be many loose papers out there with little or no comments (like on axiv currently) only a few will get the seal of approval.