[Lord of Nukes]

If the game lasts long enough, you can max the map with Overlords.

A reverse of that strategy is to build an engineering Bay behind someones resoruces, then fly it over their minerals (early in the game, and only on fastest obviously), then attack their command building. if you did it early enough, they won't have anything to attack with other than workers, so they'll kill your attacking SCV with their workers, then find they can't right click on their resources because of the Engineering Bay. They can't do anything about it unless they have the money to make Spores/Cannon. This is bad against Terran for obvious reasons. You could also use Overlords if you packed them tightly together, but to get 3 or 4 Overlords over there in time to ruin their economy is difficult.