UrlbarExt is a small firefox add on which adds amazing functionality in your firefox location bar like you can copy the URL wit ease, search the site in google, go up to the navigation tree on the site, add tags to the URL, and also lets you surf the URL anonymously through free online proxy servers.
Specially the tiny url would be really helpful for a blogger like me to shorten links for twitter, copy option can be really useful to copy the URL to clipboard for writing purpose. UrlbarExt extension easily integrates with the firefox location bar.
It also allows anonymous surfing of any URL you type in the location bar with the help of free proxy servers available. You can easily configure the extension as per your usage like changing the URL shortening service from default tiny URL to some thing else.