Rating Stone is a slightly less evil reputation system. Here you can vote up, down or "meh" on all sorts of things. Find those things easily using our category tree. Unlike other systems, we've made it slightly less evil - it forgives the past and avoids appealing to the addictive side of Human nature.
You can find out more about Rating Stone's theoretical underpinnings in the related essay A Less Dystopian Reputation System.
This is a resume fodder project (likely I'll be the only user - best rated person in the world!), layered on top of the Ruby on Rails Tutorial sample application. Also, for this project we're learning the Shopify Ruby Style Guide.
You can find the source code and submit bug reports for this web site on GitHub in the RatingStone repository. The blueprint for the project is the database design documentation, which I'm gradually implementing. Look there for how the security model works, how replies and groups are connected by Link records, and so on.
By the way, this started as the home page for the Ruby on Rails Tutorial sample application. The Ruby on Rails Tutorial is part of the Learn Enough family of tutorials, and is both a book and screencast series to teach web development with Ruby on Rails.