I saw this really cool presentation at CodeCon one time... and stole their idea. I'll have to find a link.
The goal is to automate a specific type of debugging. After you get tired of sprinkling print statements through your code, and have become dizzy from all of the layers and layers of calls during an interactive trace, you start commenting out huge chunks of code to minimize the problem.
Chompie is an automated way to do this last type of debugging. You give it a file and a tester. It will chomp down on your pogram until it's gotten the smallest thing it can while still having the same result from your tester.