So... I found a user and her profile is basically a gold farmers ad for diablo 3 and WoW. What can I do about this?
If it's outright spam, flag a post by that user for moderator attention and explain what's going on.
I have to disagree with @LessPop_MoreFizz: I don't see how anything in a profile could be considered spam, really. According to Rules for Profiles:
Generally speaking, your profile is (to an extent) fair game, as it is a reflection of you as a person, not the site as a whole.
Self-promotion, your e-mail address, humor, (if you know HTML) imagery and even the f-bomb are allowed there.
There are reasonable limitations for all of those, but generally speaking, unless you're a hard-core spammer or you put something truly offensive / crazy in there (like hate speech or pornography), you'll be OK
So if I own a gold-farming business, or a poker website, or a business that sells male-enhancement pills, I should be allowed to advertise that business in my profile like any other business - whether or not you consider those businesses to be "spam-ish" is irrelevant.
As long as the user is not advertising their gold-farming business outside of their profile (which would be considered spam), or creating multiple accounts or other obvious abuses, I say, let it be.