emacs
The EMHACKS project goal is to provide a set of useful libraries to help
using Emacs or XEmacs.
Among those libraries you will find:
gdiff, Use an external GUI diff tool from [X]Emacs;
jjar, Java Archive builder;
jmaker, Java Makefile generator;
swbuff, Quick switch between Emacs buffers;
tabbar, Display a tab bar in the header line.