I appreciate both ExifTool and ExifToolGUI very much and use them all the time.
There is one suggestion that I'd like to make: implement an option for setting the DateTimeOriginal tag for a bunch of files simultaneously, but with a specifiable relative offset for each file.
That way, one could set, say 10 images with, say 1 minute offset for a series of pictures with messed up metadata.
The only tool known to me that does this is EXIFER, but it is not maintained anymore.
Thanxx for considering it, Mixx