I worked at one. A little digital PBX company, nearly past being a startup. It was profitable (albeit only just) pre second-round of funding - and we were past that and growing slowly. But it was a hardware company (my first - I was building near-real-time device level stuff) Not an 'Internet' company. But the disappearance of tech funding caused it to fold. As a software guy, I used to kid about how odd hardware was: build one, sell one - and there are no more. With software you can keep selling.

I saw some other telecom companies fold at about the same time - mostly undersea cable companies that had made decent bets about future usage but got caught short.

There was a lot of collateral damage in high tech fields NOT involved in dot com, simply from the sudden funding squeeze. We all saw the irrational exuberance over in the web world (major reason I moved to a hardware company). The mistake was in not realizing what a crash would do to everyone in tech.