Greasemonkey Review
Greasemonkey allows you to modify every aspect of your favorite websites. With lots of ready-made scripts and the ability to customize almost any website in Firefox, it's perfect for those with Javascript knowledge. The program is easy to use, but it's important to note that it may affect the functionality of certain websites.
If you have some basic programming skills, Greasemonkey enables you to adapt a website just the way you want it by creating scripts. It simplifies the process by helping you find and create scripts online. Similar to Yontoo Layers, Greasemonkey is a Firefox plugin that allows you to apply JavaScript to web pages, altering their appearance and behavior. You can enable or disable Greasemonkey plugins at any time.