Current demo at http://www.stef.be/bassoontracker/
There's already a little "disk operations" section with some modules but it would be cool to integrate with your API to load up charts, artist lists and mods.
Application type: tracker
Platforms: modern browsers on desktop and mobile
Predicted demand: not much ... a few 100 a month I think
Commercial interest: it's a free and open source app (source is at https://github.com/steffest/bassoontracker