ViewSourceWith for Firefox and Thunderbird

Firefox users can

• open page source as DOM document
• open CSS and JS files present on page
• open images using your preferred image viewer (e.g. GIMP or ACDSee)
• open PDF links with Acrobat Reader or Foxit Reader or what you prefer
• edit textboxes content with your preferred editor and automatically see modified text on browser when you re-switch focus on it, this simplifies wiki pages editing
• open server side pages that generate the browser content, this simplifies web developer's debug
• open files listed in Javascript console. When editor opens file the cursor can be moved to line number shown on javascript console, read js faq
• for desperate cases Microsoft IE can be added to editor list.

Thunderbird users can

• view the original messages received
• process messages to extract special infos from headers
• view attachments using different applications from default