HCI researchers lack low-latency and robust systems to support the design and development of interaction techniques using finger identification. We developed a low-cost prototype using piezo-based vibration sensors attached to each finger. By combining the events from an input device with the information from the vibration sensors we demonstrate how to achieve low-latency and robust finger identification. Our prototype was evaluated in a controlled experiment, using two keyboards and a touchpad, showing single-touch recognition rates of 98.2% for the keyboard and 99.7% for the touch-pad, and 94.7% for two simultaneous touches. These results were confirmed in an additional laboratory-style experiment with ecologically valid tasks. Last we present new interaction techniques made possible using this technology.