I am finding PM tremendously valuable as my central tool from which I launch various external tools that I use in my photo editing flow. Some of these external tools are for viewing (e.g., PhotoMe to view EXIF info, VLC to view a video) and others are for editing (e.g., noise reduction, pixel editing, etc.).
It would be even more efficient and more enjoyable to be able to assign shortcut keys to external editors (in addition to "e"). Right-clicking on a thumbnail and using Edit Photo With... is pretty good but it is a bit of a "hunt and click" as compared with, say, being able to assign F9 to F12 with one's fave editors, or maybe assigning Q, W, E, R, T, and Y, or other set of keys.
Thanks,
Peter