No one has talked about good Zerg micro :-/ I micro as Zerg still, it's just I pay more attention to macro so that I have the proper units to micro with. Good examples of common Zerg micro are plaguing Terran structures (supply depots usually) to watch them burn, dark swarming cannons and sending in Zerglings and Ultralisks to destroy them, making sure your Guardians don't get too close to cannons/turrets while attacking them (that happens if you just let them 'attack-to' a point), and one of the most essential buildings involved in advanced Zerg microing, building Nydus Canals.