Basic Spy: You send a spy into the country to look up some basic facts about the economy, including resources, hidden treaties, and cash.
Military Spy: A spy gets into the enemy's military, attempting to discover info about troop numbers, placements, and nukes.
Tech Spy: A spy breaks into an enemy's research lab, hoping to steal info on a new invention.
Cause Dissension: A few 'insiders' spread the word that the government is plotting against the people of the enemy country.
Assassinate: You send a spy who attempts to kill an important leader of the enemy country.
(More to come?)