Please check out the punch acceleration sensor i've built to measure a strength of the punch as it lands on the target. ADXL193 250g single axis accelerometer is used to measure acceleration which is then sampled using AD7680 16bit A/D converter. Arduino computes maximum acceleration in G and displays it on a 7 segment LED display:
Detailed description of results and hardware as well as drawings and Eagle files are available. Software description coming soon.
This is a very cool project, and nicely detailed. I really liked the explanation for the use of the 16bit a/d converter, and the graphs really explain it all.