Before I even start this post, I want to just make sure I am clear on one aspect. If I am level 90 and invite another level 90 from a different CRZ to join my party, he/she is transferred to my CRZ, correct?
If so, I think people should start trading battletags. This week I've seen Scourged Whelpling spawns, a Minfernal (that a single guildie that was online didn't have time to reach before horde showed up), Silithid Hatchlings today during a Sandstorm, and Baby Apes.
I basically have a daily quest routine that I follow. During this, I always make sure to fly over areas where these rare pets spawn (well, except for the Baby Ape, but I do check on that one occasionally if it is near the time for the Gurubashi Arena event, as I'm working on that achievement. After doing my Molten Front dailies, I'll quickly fly back to see if a Minfernal is up. It only adds another 30 seconds to my routine, so it is no problem at all. While doing the Northrend battle trainer, I always see if any scourged whelplings have spawned, since I literally fly right over it as I approach the argent tournament. I then take a quick detour to Storm Peaks to see if it is snowing.
All these times, not a single person was on that I could help out and give them an invite so they could tame some of these pets.
I'm alliance. If you want me to inform you if I find any of these rare pets up when we are both online, please, feel free to add my battletag: animal#1402.
I'll broadcast a message to all my friends if I find a rare pet up and anyone who wants in I'll send an invite. Since I play the late late evening to early morning hours, perhaps this would be helpful to some, as like I mentioned before, there are normally nobody online for me to inform that these pets are up and they are just wasted.
Perhaps this is something that others could do as well and we could create a "network" of players helping each other out to get those few rare pets that some people may be missing.
EDIT: If you add my battletag, please put a note that you are looking for pets, even perhaps list specific ones you need if possible. Otherwise I have no way of knowing you from a gold seller spamming friend requests. Thanks