Richard Kershaw of Quality Nonsense just launched a Firefox extension that makes it super easy to lookup domain names. The extension lets you perform one click domain searches at your registrar of choice using the selected text in your browser window.
It’s super-simple: select the text for your domain search and hit the keyboard shortcut (CTRL + SHIFT + D by default). Alternatively, you can right click for the contextual menu and hit “Domain Lookup for…”.
You can learn more and download it here: Domain Lookup Firefox Extension