Here's my report for the Black Bone Spider!
I looked up the available ones, and decided to try to go for Taladorantula. It's a vignette I'd never gotten before, so I figured it might be fun. I'm into unique pets like that, even if the model itself isn't unique. I wasn't sure exactly which spiderlings I was supposed to smush, but I eventually read on wowhead that it helps to have critter nameplates. So, I began smushing them with my mount.
It didn't take too long for Taladorantula herself to appear, and she wasn't too pleased. I figured she would be large, but my goodness, she's enormous! (Technically this picture is the second Taladorantula that spawned, as I tamed the first one but forgot to take a picture.)
I quickly settled on the name Vengeance, since she spawns after you smush a ton of her babies.
Her name is also perfect for PvP, and she's a spider so she's naturally already pretty good at that with that handy web spray. So, off we went to do some battlegrounds!
Afterward, I figured I should get started on the new Dalaran questline. Here we are in good ol' Karazhan. It brings back memories..... She also seems right at home here.
Once we finished that, I headed to the Molten Front to do some dailies (trying to finally acquire that hippogryph). She ran over this puddle of lava and I noticed she looked kinda cool, so I went back and took a pic of it. I think this is my favorite one from tonight.
Lastly, I took her to the Isle of Giants to get more dino bones and a primal egg.
Probably best if we don't anger Oondasta.....
So, the verdict: I rather like this gal! I've already got a spider (Naphtali); but oddly enough, before this challenge, I'd been taming random lava spiders in the Molten Front because I guess I just felt like I wanted another one? For some reason I always feel bad taking Naphtali into PvP where she gets hurt. She is best suited for PvE activities where we can keep each other safe. Vengeance, however, seems right at home in PvP, so I think I will keep her specifically for that. I'm also quite fond of the fact that she's a special spawn, it makes her more endearing to me. And while I didn't really think I cared much for the bone spiders in particular (though I think they're cool, just not for me), this coloration is particularly pretty. I really like the oranges and reds and such in addition to the black. So, everything about her - from the spawning to her new name - really comes together for me, and I think she's a keeper.
Unfortunately, I forgot to get swimming and combat pics (I always forget in the heat of combat), but I really like the spider animations in this game. When they swim, they kinda look like an octopus. XD They're not too noisy, making little hiss noises, and I think their idle animations are cute with their little pedipalps twitching about. They often seem to have an air of curiosity about them. Oh and if I remember correctly, when you run through snow, they make itty bitty spider footprints!
Thanks for reading, and for the new friend!
I feel like someone has tried that idea with a hunter, or that it's been brought up before, but I can't remember. I think it would be fun so long as you spaced out the challenges, otherwise I could see a lot of burnout happening making reports. 
I'll keep checking! I'm camped on a hill right behind the house so I can log on periodically to check for it.