Shoutbox

It's just a basic one but i use it. basically what it does is change the search link in the navbar to a javascript link which brings up a box on click. like a quicksearch box. with a username and keyword search. but if you want to go more advanced just click the advanced search button and the old search page comes up.

to install, unzip. drag it into firefox and click Tools -> Install User Script.

you have to have greasemonkey installed for it to work though.

enjoy =)