The ultimate web app

This program is totally possible, and to be honest I’m surprised that nobody’s invented it:

A sidebar for Firefox that shows all discussion around a webpage after you browse. Every time you load a page it refreshes with information:

• any friends who have shared the page
• social media comments (Facebook, Google Reader)
• discussions about the page on forums
• blogs and websites that link to it (including wikipedia, etc.)
• aggregated reviews from the relevant sites: Yelp, Rotten Tomatoes, etc.
• related pages
• greasemonkey scripts and other web actions – for example, when browsing a Facebook photo album you see the option to download the whole thing, which has been engineered but someone on the greasemonkey site.

Build it with less than $5k, put ads up, make the world a better place. Most of these APIs are already in place.