A simple sinatra app to relay Github post receive hook notifications on to Jenkins to trigger a new build. I built this because Jenkins was triggering a new build everytime something is checked in on any branch.
This uses a tiny bit of logic to decide if the referenced commit relates to a branch we're interested in building, and if so, sends a post on to the jenkins build server.
This most probably would have been best written as a Jenkins plugin, but I know Ruby best so this was quickest for me.