http://markupconverter.com/
The functionality is very simple: it's just a web service to convert markup from one format to another, usable via the web or through a simple API.
When deciding what to do for the sprint I realized that making something simple and useful would be the best approach for getting it done by the end of the month as a side project. This also gave me the opportunity to put to use a couple markup-related libraries I put together for other projects and work with MongoDB, which I had previously only used for email storage for a landing page. Most of the conversions in the app are done by the Haskell library Pandoc, but I'm also using Discount, Python's Docutils and Ruby's RedCloth for better support of certain markup languages. The next step will be exposing more options, eg, autolinking HTML, including headers for RTF, etc.
Anyway, it's not nearly as ambitious as many other projects, but I think some people might find it useful. Any thoughts?