For CEOs of the pre-www world, July 10, 1985 was a terrifying example of how trying to fly too close to the sun could leave even the mightiest corporate wings up in smoke. It's a day that, up until April 2006 - when an obscure young search engine called Yahoo! debuted on the NASDAQ and commanded with it a $1 billion plus valuation - few forgot. But like all history, it's one that might serve the CEOs of today's web giants well if they revisited it.