College Of Computing @ Georgia Tech have a great DIY Bluetooth accelerometer, source and schematic included —

This is a small wireless sensor platform providing a bluetooth SPP link to three axes of accelerometer data. The accelerometers are sampled by a PIC microcontroller (onboard ADC) at roughly 100Hz (rate can be changed via firmware). Data from the ADC conversion is sent to a remote computer using the PIC’s UART in conjunction with a drop-in bluetooth serial part. Even with two dual-axis accelerometers onboard there are up to 17 free I/O lines and two additional ADC channels depending on the device configuration. Three sockets provide access to all PIC signals. Over-the-air programming allows for easy firmware updates and rapid prototyping without the need to have a PIC programmer or special cable. Schematics, parts lists, and firmware sources are available online.

Contextual Computing Group: Bluetooth Accelerometer – [via] Link.