In a discussion on HackerNews that went a little sideways, I left this comment:

I haven't seen much original on the internet. Almost every "new" idea I have seen on the Net I saw in print in the 1980s or 1990s. Even if the software is just now catching up to the ideas.

Thinking about it more, I cannot think of a single new idea that I have read in more than a decade.  The closest is Robin's take on the primacy of status and signalling, and even that is really just an extension.

So what are your candidates for really new ideas?