A data collection device made by Texas Instruments for science students. The standard probes included with the device measure light, temperature, and voltage, although a number of other probes are available for other tasks, like measuring pressure, pH, heart rate, and motion, etc. Compatible with the TI-82, TI-83(+)(Silver Edition), TI-86, and TI-89. For first time use with a particular calculator, the included program DataMate must be installed (it's only a button press or two), and some calculators are sold already having this program loaded.
Information on compatibility from the Texas Instruments website. Other information from what I remember of my chemistry teacher's introduction to them in class. They're fun.