One of our readers sent in the really interesting data logger. It uses an Arduino to capture the Nunchuck’s accelerometer data and stores it to the eeprom.
I used a Microchip 25AA512 eeprom. It holds 64000 bytes. Normally the accelerometer data for each axis is in a range of about 1 to 1000. I scaled that down to 1 to 255, so that I could fit one accelerometer reading to a byte. By doing that, the eeprom can hold over 21,000 nunchuck readings.
Read more about the Wii Nunchuck data logger