Disable the logging of outgoing email messages, unless you don't have a problem with anyone reading them. A site can learn a lot about you, even without Netscape or Java. With extra logging options a site can log your OS, browser, e-mail address, hostname, and last site visited. This is NOT using JavaScript either. Some companies use this info to build mailing lists, and track all of this info.
Instructions are at the anonymizer site, and it is currently a free service.
Mosaic 2.2, and all previous version of the NCSA Mosaic for the X Window System had a serious security hole that would allow telnet URLs to execute an arbitrary UNIX command. In Mosaic 2.3 this bug was fixed. This is a documented feature that cannot be activated accidentally. It must be configured. The same goes for Netscape.