How can I stitch a set of images together? I have a set of images that are named foo-N.jpg, where N is a number from 0 to 100.

I'd like to stitch them together such that I have one long image, where foo-0.jpg is at the left and foo-100.jpg is at the right.

I can do this manually in Photoshop or Fireworks, but it'd take forever.

Is there a way to do this in bulk, like perhaps with Automator, Terminal, or an app?
You can do it with Imagemagick from a terminal. If you have Homebrew, installing it is as easy as:

brew install imagemagick


Once you have it, open the terminal and go to the folder where you have the pictures, then do:

convert foo* +append result.jpg


And there you have it, your 100 pictures in a row. You can also make a column with them, instead of +append use -append.