RockScript is the world's smallest Java-based JavaScript interpreter, runs smoothly in any J2ME phones. The binary size of core engine including native objects/methods is less than 25K (obfuscated & JAR'ed). It can be integrated into any J2MEapps.
Hammock is a Java ME mock object library for testing J2MEapps with J2MEUnit or JMUnit. It includes mocks of many of the MIDP classes. A HammockMaker utility lets you mock other classes. The software includes an Ant task and Eclipse plug-in.
WorkingCode gives you what the name says working pieces of codes in Java. We are talking about code snippets and full utility apps for Java and J2me. It's use is intended as a library.