Sid Meier's Civilization

You can make settlers build mines, roads, irrigation, etc. in one turn (instead of the normal 2 - 12). For example, make the settler unit build an irrigation. The turn moves on to another unit. Find your settler and click on it. Clear settler's orders and put them back to work (press I). Repeat these steps a few times until the desired advancement is built.

Send a diplomat to a rival city and choose the Investigate City option. You get a city overview screen much like the one for your own cities, and while most options have been disabled, some were forgotten. You can unfortify any units in the city and even sell one of the city's buildings; and get the money in your coffers!

It is perfectly possible to build roads and railroads on the ocean by bringing a settler there with a boat. While they don't make ships move any faster, railroads *will* provide the usual 50% to all resources bonuses to ocean squares used by a nearby city.

Sentry a unit in a city on its last turn, then go into the city and unsentry it. It will have all its moves back.