I wanted to learn how to use d3.js for data visualization. I ended up learning about node.js and express.js too! And how to interface mongodb with all of these packages. So that was fun!
To run, you will need node.js >0.8 (I recommend using nvm to install node.js and npm for all packages).
Then cd into the cloned repo and type:
node app.js
This will open a node.js served on:
localhost:3000
For a preview of what this app looks like (provided the server is running):
Note, this works best in Google Chrome.
Enjoy!