'I found my most productive fifteen minutes were when a friend said, out of nowhere, "want to see who can do the most work in 15 minutes?"'

That's interesting, because historically great works have been accomplished when a group of really talented people get together in the same place (e.g. Florence, Silicon Valley, Manhattan Project).

The Internet is great in that it enables you to find like minded people and bounce ideas of them. But that's only half the achievement puzzle. The other half is pestering each other to work, which the Internet is not so good for.