[LukeShu]

As RobSis noted, you don't have to enable it in your browser, you can use appletviewer to run individual applets without the browser:

    $ appletviewer http://tropic.org.uk/~crispin/quantum/

And also, moderns browsers allow you to have the plugin installed, but disabled unless you activate it on a specific page.

[kecks]

Modern browsers... except Google Chrome, which has at least 40% market share.

Google Chrome does not support applets in any way since the deprecation of NPAPI.