I'm not sure if this would be uber-useful or if it would drive you crazy..
https://addons.mozilla.org/firefox/2207/
Cooliris Previews 2.1 for Firefox gives you the power to browse faster and send links instantly.
• Simply mouse over the Cooliris link icon, and a preview window will instantly appear to show you the underlying content. No more clicking back and both, or leaving your current page.
• To email a link instantly, just right-click on any web page.
• Right-click on any phrase to have Cooliris automatically do a subsearch in Google, Wikipedia, or a dictionary.
• Customize how and when you want the preview window to appear.