GistView:

This website is a simple viewer for code examples hosted on GitHub Gist. Code up an example using Gist, and then point people here to view the example and the source code, live! The main source code for your example should be named index.html. You can use relative links to other files in your Gist. You can also use absolute links to shared files, such as CDN-hosted jQuery, Polymaps, Raphaël, etc.

Want to see an example?

Checkout these pretty streamgraphs done in d3.js