I'm looking to translate various physical motions into something a computer can read/record/etc. It doesn't have to be complex, we're not talking a wii-mote here; just as long as the machine can register such movement taking place. In other words, provide immediate feedback. Now the tricky part; how to do this without using any specialized equipment outside of what your average computer schmuck uses daily?

Some computers have sudden motion sensors; also consider webcams.

Not sure what sort of movement you're hoping to catch, but isn't that exactly what a mouse does?

Aside from the accelerometer that is likely embedded in a laptops harddrive. You could also query the presence of WIFI to get an extremely course position change indication. Lost wifi? either i or the wifi moved.. probably me.

If you really wanted some data though, get a usb accelerometer. You can probably find one "cheap" at http://www.sparkfun.com.

Your question was not very specific as the above poster pointed out. What kind of movement exactly are you hoping to capture? Theft protection? User Input? Earthquake measurement?

Thanks for the responses. :)

The accelerometer is tempting to play with, but it's specialized equipment, so I'm hesitant. The use of wifi did cross my mind but I wasn't sure how accurate it could get; I don't think I can use it for my purposes.

You've given me something to ponder over, thanks.