15 Pool Fast Expand
The 15 Pool Fast Expand has become the general purpose opening for Zerg players who are trying to get an economic lead. The build is flexible enough to allow for a Queen after the natural Hatchery is planted, as well as several Zerglings to fend off early pressure. The Zerglings can be foregone in favor of Drones as well for increased early economic advantage.
To get down your expansion fast but at a minimal risk of being rushed early on, since static defense was buffed, Spine Crawlers at the expansion can be very useful for defending the Natural Expansion.
Basic Build Order
Scouting and Adaptation
A 9 Drone scout may be appropriate on some large maps like Kulas Ravine, but on maps with short distances between main bases, a scout after Hatchery may be more appropriate. It's vital to determine exactly which build your opponent is going for and to react accordingly. If you scout that your opponent, regardless of race, is going for a dedicated 1 base bust, then getting a few Spine Crawlers may be prudent. Similarly, against a fast tech build to an air unit such as Banshees or Void Rays, then a rush to Lair and Hydralisks will be necessary, but another tool to make use of is to get two Queens and keep them together to serve as a temporary anti-air solution.
The primary factor to look for when playing against Protoss is a 2 Gate, at which point it is necessary to immediately plant a Roach Warren and delay the Protoss as much as possible with Zerglings. Once the Roach Warren pops, then it should be possible to drive back the Zealots.
Terran might attempt to go for a fast Reaper or fast Marauder build, but that should be scouted with your Drone scout. Against a fast Reaper, the key is to keep the Zerglings on Creep in order to get that extra speed boost against the Reaper. Against Marauders, you should try to surround the Marauder as best you can or force it against an edge so he cannot micro against your Zerglings.
Once your Queen is finished, you can transition into any of the following builds:
This build is viable on all maps with long rush distances between main bases such as Desert Oasis.
This build is weak on any map with short rush distances between naturals such as Steppes of War, but it can still be used. This build should be avoided on maps where one might expect an aggressive opening such as Blistering Sands.
Go to near any of IdrA's replays in the smuft's team tourney linked below and you will see this opening. http://www.kriyadesign.net/downloads/STBreps.rar