>Hi,
>Motorola makes a 40g acceleration sensor (senseon is the name). so,
>depending on the precision you require, you could go up to there. For

Nah

How about building one for a few dollars.  It's a really good design, only
stores information about impact-events occuring - save wasting memory.

You have a little flashing led on a spring.  When there is an impact the
spring will stretch and the led will move.  Under the led is a piece of
photo paper which gets exposed by the led.  When you've finished measuring
you just develop the paper.  As you know how fast the led was flashing you
can see what the acceleration/deceleration was by the distance between the
dots.

Simple.
Use a PIC for the LED flasher though :)