Passwords Cleaner (Eraser) от Andy Portmen

"Passwords Cleaner" is the easiest way to clear your browser stored passwords for a specified period. You can define a custom period on the options page. Also, you can define the area (zone) in which you want the data to be cleared.

For a more comprehensive cleaner try my eCleaner
https://addons.mozilla.org/firefox/addon/ecleaner-forget-button/

Using this extension it is possible to wipe cookies of three different zones:
1. Normal websites,
2. Protected websites (not supported in Firefox yet),
3. Extension zone (not supported in Firefox yet)

Definitions:
-> Extensions zone: Extensions and packaged applications a user has installed
-> Protected websites zone: Websites that have been installed as hosted applications

For bug reports please visit:
https://github.com/andy-portmen/ecleaner