The beauty of the Favlet is that it can access any part of page currently opened in the browser. You can access any DOM elements of the page in a variable and then you can use that variable to display property or to modify it.
Installing Favlets is as simple as bookmarking web page in your browser. Simply drag Favlet to the Favorites folder of the browser and thats it. After adding Favlet, open any web page and click on that Favlet.
Here is the small tutorial if you need more information on understanding and installing Favlets in your browser: How to use favlets Bookmarklets - Browser Power About Bookmarklets
Following is the list of Favlets from my web development tool box: