Resizer is a little tool written in Perl by Sandro CAZZANIGA, based on Imager. It takes pictures to resize them at a size, and it can handles as pictures as you have in one time.

For example:

 $ resizer JPG 1024x768 # will resize all of the picture .JPG in 1024x768 inside $(pwd) ;)

Under the GPLv3+, enjoy it!