A friend of mine and I are playing, and Marine-Tank is just killing me. He does this very interesting double-push, where he doesn't rally his second batch of units to his first batch, instead he saves it up and does a sizable second push immediately after the first (right at the time when you think you're safe to build drones).
I don't really like the fact that you pretty much have to build Banelings against early Terran aggressiveness, or you are dead. If he keeps coming at you with Marine-Tank (with Medivac, possibly), you have to tech to Infestors, or you are also dead. Some people say Muta works, but if you mis-micro at all, you are equally dead. Fungal growth just does SO much damage to marine balls, and prevents your banelings from being kited.
But... Infestors don't really last that long against Siege Tanks. In fact, it's rather crazy. The whole matchup is all about you engaging Siege Tanks while they are moving, or your Zergling / Baneling / Muta / Infestor, or whatever combo of that you try, will explode to rapid-fire marines and the heavy splash from tanks.