install Greasemonkey

The first time that you install Greasemonkey. It should help you get to know what Greasemonkey is, how it works, and how you can get help if you're having a problem.Support and information both for end users and for script authors. http://userscripts.org/ A general purpose user script site for all browsers, with tens-of-thousands of scripts and an active community.and there a few especially useful pages here you might want to read:. The Greasemonkey Manual. The Troubleshooting (Users) page, in case you ever have problems.
Greasemonkey script that you should try :
You already know or use Greasemonkey? Greasemonkey is an add-on for Firefox (and other Mozilla products, as well as themes) that apply a script (javascript exact) to a website that you visit, ranging from changing the colors, themes, writings and even perform automatic actions such as logging and downloading.
If you still do not use them, please try greasemonkey here, install it and restart your firefox

 Simple way, after completion greasemonkey installed, it's time you install a script customnya. Please visit the hundreds of scripts in Userscript.org.  Choose one of the scripts, click the Install button on that page.If compatible, then the script will be installed after you confirm (press OK) if there is dialogue there is dialogue there new script installed. 
1. Google Account Multi-login : automatically switch your account to another (exp Gmail and Blogspot) 
2.change the layout of Google Reader you into the red and white with the font Helvetica.  
3.will list the download link in the Youtube video you are viewing with the MP4 format.  
4. Remove All Facebook Ads
5. automatically restore the sensors are most common in Indonesia's largest forum, Kaskus.Us.
6. Googel Book Downloader : read quality books via Google Books (book.google.com).
7.Google Translate Tooltip Google Translate Tooltip :
   You no longer need to manually translate the words into translate.google.com, now you can see directly the translation as a tooltip of the word or phrase that you block with the mouse.
8. LinkChek : automatically check your Rapidshare download links are still valid or not.
9.Google Ad Remover Google Ad Remover : remove the ads on search results on Google.com 
10.Facebook colour changer