Greasemonkey
Firefox add on
(Allows you to customize the way a webpage displays using small bits of JavaScript)
you need to install this to get almost all other scripts works in firefox.
https://addons.mozilla.org/en-US/firefox/addon/748/
GreaseGoogle
Google add on
(greasemonkey for google)
https://chrome.google.com/extensions/detail/apeeedokdcajckokidhdkbkflkpfpgko
Tampermonkey
Google add on
(Extension that provides Greasemonkey compatibility.even work in the latest chromium beta 9)
https://chrome.google.com/extensions/detail/dhdgffkkebhmkfjojejmpbldmpobfkfo
