Internet Capital Group was another similarly insane story, once worth $60 billion.
VA Linux IPO'd at a valuation of $7 billion if I recall, and had a roughly 700% pop on its IPO price.
Nortel and Lucent were worth $200 some odd billion, around the time Cisco punched up to $600 billion. And those are in 12 year old dollar terms; Cisco's valuation would be $900+ billion in today's dollar.
Infoseek was once worth $27 billion.
There was a great story in The Industry Standard or Wired about CritalPath, a messaging startup that planned to solve the holy grail of messaging. It intro'd with their team laughing about how a few pennies spent on a postcard had secured hundreds of thousands in new business, and that their biggest problem was dying of indigestion from growing too fast. Chuckles all around apparently. The company was worth $4 or $5 billion at the peak, and ended up bleeding out.
Masayoshi Son claimed that Softbank would end up owning something like 1/3 of the entire Internet eventually. He said he was building a thousand year empire. Softbank of course owned something like 25% of Yahoo when it was worth $100 billion, Softbank supposedly owned 15% or some odd chunk of all Web traffic, and Masayoshi was worth $70+ billion, just behind Gates.
Broadcast.com was purchased for $5.7 billion at a time when it had a mere $22 million in sales or so (and matching losses).
Yahoo paid $3.6 billion for Geocities. In that quarter, Geocities lost $8.4 million on sales of $7.5 million.
Viant, Scient, Razorfish, MarchFirst - billion dollar web development shops and consultants.
There are so many stories to choose from. Pud chronicled it well with Fucked Company.