GreaseMonkey

Gmail Signature Float – Userscripts.org

I depend on this script. I’d forgotten I even had it installed until I got my new laptop and didn’t have the script. Installed now and bookmarked for future reference.

gmail-greasemonkey – Google Code

I like Gmail. These scripts are supposed to make it better.

the user script page

Your last unconfined act of browsing, then is to the user script page, where you should be able to install it using Tools->Install User Script.