Allow modification of Mime Filetype

I have the need to upload .psd files, however I am not able to upload them. (not a supported file type) There is a place to forbid specific files, but not allow specific files (or file types) at least that I have found. I could probably spend the next 3 hours trying to fiddle with the code to allow the .psd filetype, but I don't want to... :P (I'm not a coder...)

Suggestion if this is implemented: Since icons are associated with specific files, create a generic icon for any file types that are not already defined. (this would be the easiest to implement) Down the road, maybe set it up to attach existing icons to files.
I would like to see this 'setting' similar to the 'forbidden files' section, with a list of allowed file types. If there is a conflict between an allowed and a forbidden, the forbidden would override the allowed. Anyway, I'm sure you get the idea...

Otherwise, beautifully written! I love AJAX!!