So, the waves of hunters streaming into the Molten Front are beginning to trickle out with their chosen pets. One of the more common pets we're going to be seeing a lot of, at least for awhile, are the lovely fire spiders.
While there's plenty of common ones, there are a few that are only available as rares--and only in the super hard-to-tame format. Placed as a challenge to the skilled, as well as a preventative measure against random killings, these spiders are definitely a prize for the rare-hunters among us.
We're still learning a few new things about them, too. Hunters had initially believed, for example, that the only green tameable fire spider was Kirix, a vicious rare elite. A few enterprising folks, though, found another source for this pet: a strange pack of randomly patrolling, tiny spiders with ~7k hp apiece.
These spiders, called Cinderweb Broodlings, spawn in the Widow's Clutch--but don't mix them up with the completely identical spiders that spawn from the dead Hyjal Scout. The latter, which spawn, mill about and then despawn 30 seconds or so later, are not tameable. They also have a different NPC ID. The completely identical spiders which can be tamed spawn randomly and race through the Widow's Clutch to the center before despawning. Incidentally, if you want to search for the tameable ones yourself, their ID for NPC Scan is 53753.
Wowhead and Petopia members are still trying to figure out exactly what triggers these spawns--sometimes a day or more goes by without a spawn, and sometimes they seem to swarm. The current theories revolve around daily quests somehow being related.
Oh, and one final note: as of today's hotfix, the Firelands & Molten Front tameables will be immune to Distracting Shot and Taunt, preventing hunters from losing their precious, hard-to-get pets mid-tame! Yey!