Here here, and Firefly references are especially welcome!

Yeah, they needed to have some model dinosaurs in that scene to sell it.

Love all the references, especially FireFly.

Also laughed when I heard that ogre say "We must push little cart" on my low level troll, but it probably only made sense to the TF2 players.

Isn't a lot of WotLK in a sense a shout-out to "Serenity"? "Serenity" is the only Firefly-related... ANYTHING I've watched, and seeing all those zombies still haunts me a bit (yeah, not much of a horror fan). But then I see the the coup of the Undercity and it kinda reminded me of the plot of Serenity (more from the Horde side, I think). Maybe that's just me, though...
In general, I really enjoy the general references, but only if they're done right (the MacGruber felt a bit shoehorned in, for example).

Why isnt this a breakfast topic? Seems kind of random to post it like this lol.

I think TonyMcS caught an important part: the references must make sense (or must not be noticeable) to the uninformed player.

"We must push little cart" isn't noteworthy for an ogre, who have less than ideal grammar at some points. If you've also played TF2, it's also funny.

"Curse your sudden but inevitable betrayal!" is a funny sentence, regardless of whether or not you've seen Firefly.

"The Cake Is Not A Lie (achievement)" only really makes sense, though, if you've played Portal. Otherwise it's just a random silly thing that makes your guildmates ask whether it was a triumph and/or huge success.

Successful external references bring the outside world into the game world seamlessly; unsuccessful ones substitute the outside world for the game world to make a joke.

The little pop culture references are one of the things that make WoW so awesome. Never get rid of them, and if you have a problem with them gtfo.