Exiftool is a command line exif editor written in perl. It can do almost anything to or from exif data in several different image formats. Lots of bells and whistles, I am just starting to get familiar with it. Great documentation also. I installed cygwin first (a unix like interface for pc). They're both free!
Cygwin gives you a unix like shell from which you can invoke exiftool.
I found exiftool at http://owl.phy.queensu.ca/~phil/exiftool/
there is a cygwin version.
Cygwin is at http://www.cygwin.com/
I don't remember if the perl module is part of the standard install, but you can install it from the same site.
If this is all common knowledge, please disregard.