I'm new to the corp strategy. A certain Lemon Person (who shall remain nameless) highly reccommended them a while ago, but I played alot of games where I ended up with huge empires where I was going for a domination victory, and thus went straight into State Prop, so I never used them. Until now.
My current game the map ended up being pretty interesting. It was a PerfectWorld map where I was on the Eastern part of a continent, with Ottoman to the West and Persia to the Southwest. There was a godawful big desert in the middle of the continent that kept everyone separate. I land-grabbed everything I could up to the desert edge and squeezed in as many city's as I could (twelve, mostly coastal). The AIs, naturally, started filling in the map by founding crappy desert cities (lots of resources, but no food whatsoever). This is when I saw that for me to conquer my continent (I hate to share) Sushi would come in real handy to feed those crappy cities.
So as soon as Refrigeration came in, I launched my war, and took over my continent (cakewalk - France gave Hitler more agita). And into every city went a Sushi and Mining Exec. Wow! I knew this would work, but Wow, just Wow. Mining Inc is kicking in +28 Hammers into every city, and Sushi is pushing out something like +14 food. Wow. And the culture from Sushi really helped with the pacification (this is LoR mod, btw), especially since I had to vassal Ottoman and Persia as they both had founded cities on tundra islands in the middle of nowhere that were too much trouble to completely kill.
Now I'm huge, overpowered, and drowning in hammers. A few of those crappy desert cities are building Wealth to balance the books, while the one city that I forgot to put Mining Inc in just founded Civ Jewelers and is spamming execs overseas (even more cash). Pretty much all the Victory Conditions are open to me; I'll hit Cultural in just over a hundred turns, or so, and Space or Domination just require me to build stuff. Just got the UN up, so Diplo is possible, but not likely (El Cid is big and REALLY hates me).
All I can say is Wow, just frickin' Wow.
(Oh, and I just use Spies as passive city defenders, and sometimes as "black-clad Siege").