Most of you already know the standard Fake double TvP opening from Brood War;
http://wiki.teamliquid.net/starcraft/Fake_double

I've been playing SC2 for a while now, and most people are saying that tanks suck now amongst a lot of other pretentious bullshit.
Anyways, I play random, and I finally have a feel for SC2 balance. When I play ZvT, I like to get my expo up quickly (Broodwar style), and then use my first 100 gas to get lair, so that I can deal with the inevitable marine/maurader ball with hydras and infestors.
Usually, I like to forgo roaches completely and rely on spine crawlers, but depending the amount of pressure T puts early on, I will have to make them.
After a while, I was winning 90% of my ZvT games like this. Early exp, spine crawlers to lair, tech hydras and infestors, and then engage with speedling/hydra/infestor. it would decimate the 'regular' terran ball timing off of one base.

Let's stop beating around the bush; this build which I am about to explain is VERY versatile in TvZ and has a plethora of different branches.
If I scout an early expoing zerg, usually I will consider quite a few things

First off, are we playing on a Lost Temple-esque map, such that I can do a potential thor/siege tank drop on their natural cliff. Is the expo reachable by a thor on the cliff? Or does it require tank range? A good thor/tank drop followed by some marine/marauder agression afterwards can throw off many zergs, as they will lose tons of drones, lose the exp, and produce tons of useless zerglings.

If I can't do this, I will usually rely on what my scouting SCV sees. if it gets killed very quickly, i will usually expand myself, to try to keep even in economy, while teching to starport, and then adding on more raxes.
But if my scouting SCV sees an early lair, especially with spine crawler defence instead of roaches/lings, then I will do the FD build.

10 depot
12 rax
13 gas
15 orbital
pump marines/scvs
first 100 gas for fact
2nd gas immediately after fact starts
reactor on rax
**2nd rax
tech lab on factory
siege tank and siege mode tech
attack with 3-4 scvs, tank and all marines


** the 2nd rax is optional, depending on what your opponent is doing

If I don't scout a roach warren, and I'm 100% certain that they are just skipping it entirely for the lair tech, I will usually put up a 2nd rax and try to do severe damage and take out their expo.
If I scout a roach warren, or overwhelming zergling numbers, I will forgo the 2nd rax and instead get my expo, and just siege up to protect it
If I see mediocre numbers of zerglings/roaches, I will set up bunkers outside their choke, and slowly contain them, inevitably killing their hatchery
If I see low numbers of zerglings/roaches, but heavy spine crawlers, I won't make the bunkers and instead get my expansion up quicker. if they are making spine crawlers to delay for lair tech, my expansion is up quickly too, and I will use a scan to see whether it is muta/hydra coming. (Usually most people won't be able to delay the tanks enough, so their nat will fall anyways)

The point is, this build has lots of aggressive potential vs FE zergs, but it still provides a nice timing for an expansion vs a FE-into-mass-ling/roach zerg.

Here is a FPVOD demonstrating the build, sorry for sound quality, guess my microphone picked up the speakers

Sounds pretty good to try.
Although, I've tried fast reactor hellions against Z when I scout FE and early lair. It'll hit before roach, and they usually don't have enough spine crawlers, and it usually ends with all their drones being burnt.