Last year, vise-grip manufacturer Irwin held a contest called "Tell Us Your Vise-Grip Story" where people share their personal experience of using the tool. They've chosen 3 finalists, one of which is this one by Bryan from Chesapeake, VA:
As a US Navy spine surgeon, I routinely deal with dozens of different types of screws, rods and bolts that have been implanted into the spine. Each manufacturer has their own unique tools to insert and remove their specific hardware. While deployed to the Middle East in support of Operation Iraqi Freedom, I did not have access to these specialized tools. I did however have some Vise-Grips that could be sterilized and used to emergently remove the screws and rods from this infected solider's spine.
No doubt about it - vise-grips are useful. Almost as useful as duct tapes: http://irwin.eprize.net/visegripstory/index.tbapp - via Popular Mechanics and The Zeray Gazette