If it's possible to build something this rich without Flash, I have yet to see how.

The logic for the scroller bar at the bottom is fairly complex. We've done many, many hours of usability testing with this and it actually hasn't posed a problem. But I know exactly what you mean. It's actually not bouncing back to the initial position, but it probably looks like that if you have tens of thousands of products displayed there. Try filtering to see the difference.