Remember the last time you clicked on a banner ad? Me neither. Online is the most measurable medium, but we're still largely allocating ad dollars based on raw impressions or clicks.

But what if you could know what people are looking at when they watch their screens? Eye-tracking, of course, has been used by advertisers, agencies and TV networks for years, but it requires expensive technology and specialized facilities. That's the problem being tackled by GazeHawk, which has built eye-tracking technology that can be used with any webcam.

For the display-ad business, this kind of analysis can be incredibly valuable, showing creatives exactly which part of the unit catches people's attention -- regardless of whether they click.

GazeHawk has its own testers, and will deliver a signature "heatmap" that details where people are looking and for how long. Alternatively, publishers or agencies could recruit their own panels or offer site visitors incentives to participate.

A note on the inherent creepiness of all this: Co-founder Joe Gershenson, who developed the technology as a grad student at Carnegie Mellon, stresses GazeHawk is 100% opt-in. The software first has to be calibrated with the user's eye movements, so no video or recording can take place accidentally or without consent.

Millward Brown and IPG Labs have already worked with GazeHawk, as have Mozilla and Bell Canada's Sympatico.ca.