Use the accelerator component of the App Inventor for Android with a Clock component. This prevents the accelerometer from crashing the system -probably as a result of a buffer overflowing somewhere.

I am using a G1 mobile phone, developers version.

Source Code

http://www.carloslabs.com/files/app-inventor/Accelerometer_test.zip

Blocks

http://www.carloslabs.com/files/app-inventor/accelerometer-test.gif

The moral of the story is -the clock and the accelerometer work great together-