I have been getting pretty annoyed with the image spam that has been getting through my mail filters. These are some interesting emails. They generally include an image of some text at the top of the email, and then a bunch of random text (In one case, the text was related to resumé writing and English as a second language)
I saw this page that describes how to setup an optical character recognition (OCR) SpamAssassin plugin to help identify these spam messages. This plugin uses gocr uses as the OCR engine. I have set this up, and will see how well it stops these messages from getting through.