Advertising
I haven't seen anything like this before:
I'm running AdBlock for Chrome. I suppose Wowhead coders made the site fall back to these default ads when ad blocking software is found. The exact way to do it is way above my head, but it's definitely a very smart way of reminding people that there's more to ads than annoyance.
I'd even whitelist the site if it wasn't Wowhead in the first place that made me install AdBlock: those two huge segments were usually occupied by the most epilepsy-inducing flashing psychedelia of so-called ads the internet could produce.
I didn't care about "free" green card opportunities or browser-based MMOs the least bit.