Getting university and government grants requires a great deal of gaming the system. I'd say governments and academia also attract gamers of the system moreso than startup world (indeed, that is a point that pg makes).
I can't speak of "most interesting", I can only speak of what I've worked on :-)
Distributed systems that span tens and hundreds of thousands of nodes and provide excellent reliability characteristics. A multi-year C++ project being built by a small/medium sized team. Those are just a few example (stated deliberately vague due to NDAs, etc...)
I can't speak of "most interesting", I can only speak of what I've worked on :-)