In order to include additional helper applications for Netscape, all that is needed are two files in one's home directory: .mailcap and .mime.types
In the above sample files, the required helper applications for xdvi, ghostview and uncompress as well as gunzip are defined. If you have installed a mpeg-player, mpeg videos can be rendered, too. Just download these files, e.g. by clicking on the links with pressed shift key.
If you want to add more functionality yourself, consult the documentation of Netscape on Helper Applications.
Plugins: Instead of purchasing commercial plug-in's as Netscape
expects you to do to take advantage of this newest unnecessary development,
you may install plugger, which allows you to use external programs like xanim
instead. Simply get plugger-2.2-linux-elf.so,
mkdir /usr/local/lib/netscape/plugins
and move it there.