Not a MML user myself but that's a great idea and nicely put together

Thanks Neil! I'm a big fan of your work.

I only recently started getting into chiptune composing.  Since I'm a programmer MML feels more natural to me than using a tracker, but in some ways it is limiting, and there is not a whole lot of easy to find examples/documentation. 

I decided to try writing my own language to make some things easier to do using MML.

Essentially MMLX is a superset of MML.  It offers a bunch of features that MML on its own does not support including:

- Defining instruments
- Portamento
- ADSR Envelopes
- Using variables
- Transposing

You can check out the project at:
https://github.com/ccampbell/mmlx

Getting started guide:
https://github.com/ccampbell/mmlx/wiki/Getting-Started

Documentation:
https://github.com/ccampbell/mmlx/wiki/Documentation

I should point out that I have only tested it using Python 2.6 on Mac OS 10.6 and only using the default 5 NES voices A-E.  I believe it should run on Linux as well.  I don't have a windows machine to test on so if anyone is interested feel free to fork the project on GitHub and add Windows support.

I also have included a TextMate/Sublime Text 2 bundle with syntax highlighting that looks like this:
http://f.cl.ly/items/3B2B2R12303j0E283E3b/mmlx.html

I also hope that someone else might find this useful.

I look forward to hearing feedback. 

Please report bugs and feature requests on GitHub:
https://github.com/ccampbell/mmlx/issues

Craig