Allowing filetypes
After we discovered a problem with uploading m4a files, we have now installed a plugin to allow you to change the filename extensions you want to allow. The syntax is a bit different but fear not - here are a few of the ones you are likely to want to add:
m4a audio/m4a
m4b audio/m4b
kmz application/vnd.google-earth.kmz (for google earth files)
Firstly activate teh plugin, then go to Options -> Mime Types to add more types.