Wired News:

despite no meaningful update in about 15 years... "It was and still is the most significant tool I've ever used," said Richard Wanderman, a technology consultant and, at one time, a leading advocate.

[Bill Atkinson, the developer] feels that if only he'd realized separate cards and stacks could be linked on different people's machines through the Net -- instead of cards and stacks on a particular machine -- he would have created the first Internet browser.