Searching by Scent

Why can't I search Google by scent?

If there was a way to plug a digital "nose" into my computer - like a USB-microphone for smells - could we search by smell? I had this thought after using the drag-and-drop interface for Google Images. During an early morning jog I smelled something delicious cooking, but I couldn't quite place it.

Most of my other senses are covered. I want to solve this problem. I've looked into various Arduino sensors and thought about building my own, but it doesn't look like this sort of sensor exists.

Perhaps I'm jumping the gun. What we probably need is some kind of digital taste tester first, then we could focus on smell.

Update: Someone brought this to my attention. We might be closer than I realize!