RegX is a project mainly written in JavaScript, it's free.
An attempt at a regular expression tool that apparently already exists (http://gskinner.com/RegExr/). Written using node.js and express.
This was an attempt at creating a regular expression tool that I found out already exists (http://gskinner.com/RegExr/) in a better form than I had even imagined.
Nevertheless, it was a good experience for learning some of the basics of node.js, Jade templating engine, and the Express web framework.