tuipeer and Java 2
Java 2 has broken the AWT abstraction. (Boo! Hiss!) It is no longer possible to extend java.awt.Toolkit and work with the Java 2 AWT classes. The existing version of tuipeer will not work with Java 2.
Workarounds for using text terminals with Java 2 include extending the undocumented sun.awt.Toolkit, rewriting the entire AWT package (e.g. BISS-AWT), or using an entirely different 3rd party API (several projects, including my EDX interface).
An open, cross-platform journaling program.
A scientific plotting package.