How to write Greasemonkey scripts
Greasemonkey is a Mozilla Firefox extension that allows users to install scripts that make on-the-fly changes to specific web pages. Greasemonkey can be used for adding new functionality to pages.
Dive Into Greasemonkey is a book about programming with Greasemonkey, a Firefox extension for customizing web pages. According to this book “Greasemonkey is a Firefox extension that allows you to write scripts that alter the web pages you visit. You can use it to make a web site more readable or more usable. You can fix rendering bugs that the site owner can’t be bothered to fix themselves. You can alter pages so they work better with assistive technologies that speak a web page out loud or convert it to Braille. You can even automatically retrieve data from other sites to make two sites more interconnected.”