My scanner adds annoying borders on everything it scans. I wanted to find a way to fix this with the command line. Enter Imagemagick (thanks to this site for the help.)
I found one picture and selected the area I wanted to crop it from. I used IrfanView to tell me the dimensions of the desired crop, then passed that info onto the command line. I used a bash for loop to get the job done on the entire directory:
for file in *.jpg; do convert $file -crop 4907x6561+53+75 $file; done
It worked beautifully.