Ask not what Mozilla can do for you but what you can do for Mozilla?
This project is a place for contributors to start looking for new projects to work on. This will guide you in the right direction depending on your prefered development language.
git clone https://github.com/jdm/asknot asknot
cd asknot
Start a local HTTP server. There are a lot of ways to do this but here is one for using python.
python -m SimpleHTTPServer 8000
Open localhost:8000 in your favourite browser!
Josh Matthews josh@joshmatthews.net
Other contributors listed at https://github.com/jdm/asknot/contributors