I would like to see a new checkbox option that enables using a global tag - filename format string (also stored in options). Once the format string is entered and the option checked, files will automatically be renamed whenever tags listed in the format string are altered and the information is saved. Just like iTunes does it (except the format string is user configurable, which will be way better than iTunes).
I could be missing something, but as far as I know I have to remember to press Alt-1 and then Enter each time I make a change to a tag that is part of the filename. That's alot of work for someone as lazy as me.