RubyGems.org

Continuous integration should really just be a script that captures the output of running your project update & test commands and presents recent results in a static html page. By keeping test reports in json, per-project CI configuration in 3 probably-one-line scripts, things are kept simple, quick, and super extensible. Want to use git, svn, or hg? No problem. Need to fire off results to Campfire? It's built-in. CI depends on cron.