I came across this great story on Ars Technica .
Trained rats sniff out unexploded mines. They’re smart, calm, and light enough not to set the horrible things off. And cheap, compared to the $25,000 invested in a trained dog. A Belgian outfit called Apopo  came up with the idea and has been training the rats, a special, six-pound, African species. It takes about a year, and one in four “graduates.”
Thousands of children and farmers would not lose legs, hands, eyes, or their lives if these animals could be deployed everywhere they’re needed.
Oh, and did I mention that they’re seriously cute?
Not only would lives be saved, hundreds of square miles of farmland could be returned to production if the explosives were cleared.
The rats can be trained for any work that requires a sensitive nose, such as TB scanning, as well as other diseases. Imagine it. Each health worker with her or his own little pet carrier.
The hardest part, I gather, has been getting people to fund work with rats.