Can anyone point me to some good articles/posts/etc. regarding effective use of spies and corporations? I never seem to use my spies well in the game except to defend my cities. And I've yet to successfully do ANYTHING with a corporation besides found one and then realize I really didn't want it. If I could just find an article or three on them, or a good post, they might up my game the last notch I need to hit Emperor level, but I can't find any in the War Academy.

You might want to try the War Academy, although I'm not sure if there's anything good there on those subjects. When I play, I rarely use spies; I just use the espionage points to get city visibility, see research, etc. If you need to, though, spies can be great support in wars by pillaging a strategic resource, putting a city into revolt for one turn (nullifying cultural defenses for that turn); I've even used them to destroy my opponent's space ship parts. I can't help you with coroporations, though. I find state property too powerful to mess with corps.

See MrCynical's Power of Sushi article (http://forums.civfanatics.com/showthread.php?t=237717) for the details on corps. There are several Espionage-related articles on the first couple pages of the Strategy Articles (http://forums.civfanatics.com/forumdisplay.php?f=156) forum; can't really recommend anything specific though as it's not an area of interest.

Espionage is awsome!
I had a tough game with two AI superpowers. In the modern era i took on one of them with force, the other (koreans) were building space parts quickly. Once I had enough esp points on korea I could see which cities were building the parts and use spies to infiltrate his production.

So i technically stopped one AI from winning a space victory with SPIES!, while my military force could concentrate on domination victory by destroying the other superpower.

I find that espionage is a great tool if you are ahead of some or most of the civs. The passive effect of espionage is invaluable to know what the other civs are researching. If you are behind, it is a waste.

At higher levels of play, every 10% you can dedicate to espionage takes away from your cash or research, and seems to be a poor trade-off.

The larger the world you play on, passive espionage is less effective when distributed against all or many of your enemies. If you focus your points on 1 or 2 civs, then it be somewhat helpful. In smaller worlds, passive espionage is really helpful.

If you focus your points toward on civ, it can be helpful if you declare war and can infiltrate a city and send them into civil unrest. This removes the percentage of cultural defense for one turn. This allows your seige weapons to attack the garrison units in the city more quickly.

Spy missions to change civic can help flip someone (i.e. Isabella) out of theocracy to allow you to infiltrate your state religion in an attempt for an Apostolic Palace diplomatic victory.

Put a spy in recently conquered cities. This gives a counter-espionage benefit. I find that the civ you are warring with will run a lot of spy missions in these recently conquered cities.

I suspect that if you can use espionage as your main tool to attain victory (i.e. run slider to >60% espionage), then you are likely playing on a level that is too easy.

As far as espionage goes, look up madscientist's Mao Zedong game, where he used the Great Wall and several settled Great Spy's to run what can be described as an espionage economy.

Eh... I don't like the idea of trailing in Techs just so I can steal them. I find that my goal in most games (besides winning) is having so great a tech lead that most civs can't even research what I can. Even if my power isn't as high as others, if my tech is high enough, when another power civ DoW, I use a lot of cash to quickly mass upgrade troops to tech superior units.

Then mop up their attack stack and take their land right from under them.