1. A reputation system for people who are members of the frassle community. This means weblog authors and commenters (who are really just thinly-veiled weblog authors). Since the point of the reputation system is to encourage positive behavior by people so they can get more stars next to their name or whatever, it must apply to people.
2. A ratings system for posts and items on the web. This would be a way to quickly rate the quality of a post you read on frassle, or to save a rating along with a bookmark to any random thing you find on the web.

These systems don't have to be perfect, or even transparent, but they do have to be convincing and accurate. The reputation system I currently have no great ideas for. The ratings system, however, was one of the original motivations for frassle and I think I can do something pretty cool with that.