I came across this good quality software yesterday, it is called SeisMac, and I installed it on my old MacBook, not really expecting it to work, but it did!
I was amazed by the precision of the built in motion detector. If you have a MacBook (or MB Pro) give it a try. It's pretty cool.

I was amazed by the precision of the built in motion detector. If you have a MacBook (or MB Pro) give it a try. It's pretty cool.
