Would you like to use a website in ways its page authors have never thought of? Stop being the passive read,er be active. Amend the information.
Greasemonkey is a Firefox extension which lets you to add bits of DHTML ("user scripts") to any web page to change its behavior. In much the same way that user CSS lets you take control of a web page’s style, user scripts let you easily control any aspect of a web page’s design or interaction.
For example, you could:
Some other smart extension scripts.