I’ve created lately a small j2me application framework with its own windowing toolkit. It contains features that help me develop new j2me apps in lightning speed. I developed a dozen applications based on it. For examples, have a look at www.executableknowledge.com and www.gomoby.com.
In the near future I will release some example j2me code, for the moment I am just publishing the list of links that I use the most. Microdevnet has many good articles on j2me. Check the j2me devices list from SUN. Example code you can find onexample j2me code from Nokia. Remember to check also the developers forums at sony ericsson.
To see example midlets for inspiration, go to midlet.org
Bill Day’s J2ME Archive is a good index for everything relating to j2me.
To start multiplatform development look into the j2me polish framework. It supports over 350 mobile platforms. If you need other mobile related indormation a good index is at gsm.pagina.nl. It contains a list of mobile phone manuals.GSMArena.com is also a good index of mobiles specs.