SuperCraig is a concept UI for the web that utilizes just the direction keys.
Try navigate around using ← ↑ → and ↓ (Make sure your keyboard focus is inside the page!)

 

Limitations: This prototype only works in FireFox. Live data connection to Craigslist and infinite scroll have been disabled due to Craigslist policy. Mock data are used instead. The content page is also disabled so a blank screen is displayed.