Measure everything that vibrates, shakes or moves.
Unlimited recordings (or until your iPhone/iPod disk is full, which is around 50 days using the default resolution of 60 measurements per second)
Broadcast accelerometer data
Stream raw accelerometer data to the local network using an open protocol.
Check out the demo applications:
Tweak the seismometer to suit your needs. Axis to measure, sampling rate and much more.