As hans said, the wii is very good for starting up "sensor/accel" projects. Although when you need better data the wii will not provide, so don't raise much expectations. 

At my research lab we work with accel+magnetometer to correct the values, anyhow it is now wireless for now, which is a major disadvantage of the current setup. The previous one was a wireless accelerometer-based from Plux (http://www.plux.info/) with a C++ API.

Best of luck,
Pedro

--
Pedro Lopes (MSc)
contact: pedro.lopes@ist.utl.pt
website: http://web.ist.utl.pt/Pedro.Lopes