Mass EXIF date and time manipulation

I'm out traveling and I forgot to change the timezone on my camera again. So the EXIF time stored in the pictures are all wrong. My first though was to write another Perl script to fix this (se earlier post). But I found out that the program jhead can do all sort of magic EXIF manipulation. To mass change EXIF dates, just do a:

  $ jhead -ta+7:00 *.JPG
  Modified: IMG_1708.JPG
  Modified: IMG_1709.JPG
  Modified: IMG_1710.JPG
  ...

This add seven hours to the EXIF stored time. Nice and easy.