I am finally happy with the current build so I am cutting another release. The first version of the file browser is complete. It will only let you navigate paths you have added to the scanner. I also added an about dialog to show some extra information.
I also recorded a video of the app on my archos.
The only issues i've ran into so far is the songs view can get extremely laggy when your collection is like 50k songs. I will do some work in the future to make that view a bit more responsive for large collections. Also on my thunderbolt I sometimes have to touch the buttons in the quicknav twice before it registers the press. Otherwise I am not aware of any other bugs. Please post if you find any issues.