When playing zerg against zerg send a drone out to scout for ur enemy. While doing this keep pumping out guys and get a spawning pool. When u do find ur enemy with the drone take him to the back of the minerals and start building a creep colony quick. Dont forget to keep getting guys,OLs,sunkens, and lings. When ur creep colony is dine turn it into a sunken quick! If u do get ur sunken built u will be taking out his workers really quickly. Usually the person leaves but if he doesnt and he kills your sunken then u should have a lot of lings built up to finish him off. (This DOES NOT work on comps, and is only effective in a 1v1 or a 2v2).
Good Luck!!!

CreepColony's Opinion: I guess this is against a zerg opponent, since you need creep. And I thought it did work against comps...hmmmmm....