Here’s a nice utility made by Julien Letrouit. It is a small on-brick program which allows control one or two motors. This can be useful to test your robots without the need to use your computer.

Description: 
This program written in NXC (http://bricxcc.sourceforge.net/nbc/ for more information on that language) allows to test the motors while building your robot. This is handy if you don’t have a computer close to you when building a robot.

Content of the zip file:
  - TestOutput.rxe: the program to download to your NXT brick
  - TestOutput.nxc: the source code of the program written in NXC 1.0.1 b24

Installation: 
Use the download feature of the NXT window in the NXT software to download the “TestOutput.rxe” program to your NXT brick. 
Usage: 
Launch the program on the NXT and follow on screen instructions. Selecting “A”, “B” or “C” will allow you to test one motor at a time. Selecting “A+C” or “A-C” will allow you to test A and C at the same time. With “A-C”, C will go reverse compared to A.