If you are heavy RSS/ Atom feeds user you might have been disappointed by Mozilla’s decision to remove the RSS button from the address bar. The good news is that the functionality is still there, albeit further away under the bookmark menu.
A better option is to add back the RSS button to the navigation bar. To do so, right click on the Firefox button, and under Options click on “Toolbar Layout”, this will open dialog that has a number of widgets that can be added to the add-on bar or the navigation bar. There will be a button labeled “Subscribe”. Drag this to the add-on bar, navigation bar or even the tab bar and menu bar!.
You can now click on this button to get the same functionality as the RSS button in the Firefox 3 address bar offered.