The DOD is working with two university professors to see if it's possible to create rat-based mine detectors. The idea is to train them to circle a mine once they've found it. A tiny GPS backpack they're wearing would allow a computer to "spot" the behavior, and therefore the mine. The rats are too light to set the mines off, so they'd be safe. Not sure how they'd collect them after the job was done, I guess you just pick them up from their circling.