I want a plug that will help me monitor the internet activities of some of the employees (and the owner) of the company that I work for. Upon visiting the mozilla firefox page, I find there are no plugins that will do what I am looking for. There are a myriad of different plug-ins however, which got me to wondering how they are made.
Not really making your own plugin, but I believe Greasemonkey is an extension that is built to let anyone with some experience in javascript control the functionality of Firefox.
Might I suggest that a browser plugin might not be the best way to tackle your problem. Sounds to me more like you want some kind of proxy server with logging functions - that way, it will still log the activities of your employees even if they use a different browser.