Nowadays, people know a lot of other people through podcasting, blogging, social networks, Twitter and forums that they've never met in person. People work together with "strangers" to develop cool software, they help each other out on support forums, people like Chris and - on occasion - myself write articles for CyberNet although I have never met Ryan or Ashley in real life (and I presume Chris hasn't met them either).
If the internet were to crash, all of that would be gone in one swoop.
Then again, that's pretty much impossible, so whatever.
I think there are 11 DNS servers around the world responsible for keeping the internet running. If they were to crash at the same time, the internet would collapse. Even decentralized networks such as BitTorrent and FastTrack would be broken immediately, as they still need to fall back on IP adresses.
Also, I read about something called an eBomb back in - I believe - 2002. In theory it doesn't damage anything other than every power plug, battery and electronic device in a certain area around the bomb. Imagine if they dropped an eBomb on Silicion Valley or each and every of these servers. That could make our entire economy collapse...