Free alternative to Eye Tracking

The latest issue of http://www.softwareceo.com (July 2007) had an article about "Heat maps for better web design, marketing benchmarks, and a dead software CEO".
Feng-GUI heatmap service was recommended as a free tool for simulating the movement of visitor's eyes on a web page.

here is the article:
http://www.softwareceo.com/attachments/fenggui/tip072407.php

Thank you SoftwareCEO !