[MOD-Request] How did you hear about us

I would like to see a "How did you hear about us" MOD to be added to the checkout. It would be nice if it had the ability to enter in your own fields... i.e., Email, Radio, TV, Net, etc...
Then it will need a way to report what the users select in a report so yo will know where your traffic is coming from.
It seems nearly every e-commerce site I have gone to lately is asking me How did I hear about them. I think this would be a great addition to OC.