Both Linky and Launchy in Best Mozilla, Firefox & Thunderbird Extensions posting
Linky: Linky will increase your power to handle links. It will let you open or download all or selected links, image links and even web addresses found in the text in separate or different tabs or windows. You will just need to right click any link or web address, select the Linky menu item and choose the desired action.
Launchy: Launchy is a Mozilla, Mozilla Firefox, Mozilla Thunderbird, Netscape and Nvu extension that will enable you to open current page, links, mailto, images and view source with external applications. Both browsers, media players, FTP clients, download managers and editors are supported. That's applications like Internet Explorer, Opera, Mozilla, Outlook, BSPlayer, Windows Media Player, GetRight and others.