Sun, Oracle, AOL, EMC, Nortel, Lucent, Cisco - all took huge shots from the ecosystem of dotcoms going under.

Cisco for example, in the 4th quarter of 2000, grew sales by 61% (55% for the year). Famously they had basically accelerated growth every quarter for a couple of years. The projections had gotten almost insane, about how big Cisco was supposed to be in just a few more years.

The money quote from August 2000:

"We see no indications in the marketplace that the radical Internet business transformation in practices like customer service, supply-chain management, employee training, empowerment, and e-commerce that is taking place around the world today is slowing -- in fact, we believe it is accelerating globally," said [then CEO] Chambers.

3Com. They basically shut down their networking division because their management and investors figured that they were now a wrapper around Palm.

At JavaOne, I remember seeing Bill Joy predicting that $1T of wealth creation was going to grow to $10T. I think this was in 1999. A few years later, he warned that nanotech may turn us into grey goo. [I may be exaggerating a bit] Birth of a pessimist?