i use this free mel script for my shelf from highend3d... http://www.highend3d.com/maya/downloads/mel_scripts/texturing/Keegan-reloadTexture-3379.html there are even a few others if you think you need more options. in this way 3d studio max rocks.
I just add the update PSD textures to my shelf. As for other file textures... don't know as I only really use psd while texturing though saving to a separate file would help with memory issues. I'm sure you can make a script for it or add something to your shelf. Or maybe one exists already?