This is one of those “under the radar, but still cool” features of Firefox 3 I haven’t heard much praise about. 

You can now search through your saved password information.  This is great for those of us who often forget what login we used with what web site and don’t want to go scroll happy going down the list to maybe find the right result.

To check it out, go to Tools, Options and then the Security Tab.  Then click on the “Saved Passwords…” button under the Passwords section. 

The rest of it is pretty self explanatory.  Type the phrase your looking for in the search box, and the list will get shorter.