This MIDlet paints something on your phone's screen. It is not much, but perhaps not bad if you have no clue how to start yet.
The source code is also available to help you if you want to get started with J2ME (or Java ME as it is now called) programming.
Here is also the source code. The zip file contains an Eclipse project to be used with the EclipseME plugin and Sun's Wireless Toolikt (WTK).