A Java GUI for applets to produce Rich Internet Applications. This project started before Sun Microsystem announced the Swing library. At the time, the only way to create applets with a GUI was to use the AWT and the results were clearly underwhelming.
I created the Macintosh Application Environment for Java to to create rich internet applications that could run within the browser without requiring loading massive amounts of remote classes. MAE for Java is extremely lightweight and writing apps that use this library is quite easy.
Over the years, I wrote several apps based on MAE for Java. The most popular was a game commissioned by the Spanish DGT agency to train drivers on the changes made to the driving regulations in the mid-90'a.
Take a look at the documentation on the project's wiki