Currently, Google. Not necessarily because they are world-leading trendsetters in all things internetty, but because they have acted as the ultimate facilitators in internet-related development over the past decade. Whether you like Google or not, the online world wouldn't be what it is without their contributions (and investments, and acquisitions).
Seriously though, I would say the fact that in theory, we can have knowledge accessible by anyone on the planet, and that's awesome. I believe on day it will.
The end-to-end architecture of the IP layer, enabling the level playing field for new apps and protocols, and letting anyone be a content provider or p2p node.
