During a physics class we were preforming a physics experiment to measure the accleration due to graivty - 9.8m/s^2 and while we did not make any new physics discoveries I had an idea for improving the experiment. The way the experiment worked was to drop a NXT with an attached acclerometer off of a balcony and some one below would catch it. The problem was that if they missed it $200 would hit the ground and shatter. After some research I found that for $50 you can build an Arduino with an accelerometer that works just as well and has less signal noise.
A few benefits to the MMA7361 Acceleromter are that it can be set to detect +/- 1.5g or +/-6g. I also have a very low power consumption and its small size even with the breakout board makes it an ideal fit for any project. Not to mention the relatively low cost.
Step 1: Materials
1x Arduino Uno (a Mega will allow you to store more data, but it is also bigger and more expensive)
1x MMA7361 Acceleromter - Sparkfun has one with a breakout board
1x Proto shield/perf board
The every project extras: