UrlChecker

Download extension

Check the status of download links from various file hosts for free.UrlChecker for mediafire, rapidshare, depositfiles,mega.co.nz,.. adfly,bitly,urlcash,linkbucks link extractor and many other file hosts
Automatically marks online status of links within selected or a webiste
This addon adds two options, one in context menu and one in status bar, in a form of an icon.

The context menu option (right click) will help you check the status of selected or highlighted file host links. So, all you have to do is highlight then click on "Check selected links".

The status bar option allows you to have all the links on the page you're currently on to be checked.

Supported by http://urlchecker.net (http://urlchecker.org)
Addon for Firefox
https://addons.mozilla.org/addon/urlchecker/