I'm sure some Zerg players have done this or seen it done but I have been bassically doing this since the early release of the game / beta, and I don't see it happen that often, so I thought it would be good to make a thread about it.
Bassically shortly after you have your natural expansion finished, both bases pretty saturated in ZvP and you will have about 4 queens just pumped nonstop after pool finished just to be safe of any pheonix / void ray play, I normally either get lair sort of early or just get evo chamber wall + spine and a spore to be careful of dt's, what you want to do is to get a queen as close as possible to his base without being seen, bring a drone along and build a hatchery as close as you can get to his choke , then lay down the hatchery , with the queen right beside hatchery cancel the hatch and use the leftover creep to lay a creep tumor, then back up and do it again in the next place , 2 - 3 times in key locations , once you've done it about 2-3 times you will have a very nice creep spread going in all directions, to his main, to the left right and back towards your base as well, and very soon you will probably connect your creep highway from his main all the way to your base in no time, I feel like this is bassically the fastest way to creep spread in ZvP, here is a replay of me doing it.
Replay : [url blocked]
In this replay I had to delay the backwards creeping because of the voidrays, but honestly you can get the backwards creeping started a lot sooner vs a forge expanding toss on most maps, although I feel that the replay does pretty much demonstrate what I am talking about, I will be doing more and more back creeping in ZvP vs forge expanding toss and will post the replays, You guys feel free to post your replays of backwards creeping as well, as i'm sure I am not the only Zerg who is aware of this, GL HF and Happy Zerging!
EDIT : You can do this in ZvT as well but it can prove a little more difficult, i'd say after stopping 1st / 2nd timing attack would be a good time to start back creeping in ZvT.