Since beginning blogging, I've discovered that, on "Christian" blogs, certain topics garner more attention than others. Want to drum up some readers but don't much care about the level of discourse? Tackle one of these guaranteed-to-rankle topics, preferably employing as little wit and as much generalization as possible. Blatant (and groundless) personal bias is optional, but helpful.
The whole hymns vs. modern worship music thing can really get folks fired up, especially if you make it out to be a boxing match in which there can be only one winner and one sore loser. It's helpful if you start by carpet-bombing the comments sections of a few blogs written by the doily-wearing patriarchy crowd. Well, the women in that crowd, anyway. You can employ this same "my position is biblical and yours is LAME and BORING" tactic when addressing whether women should wear dresses only and/or headcoverings as well.
Calvinism. Shoo, nothing gets some people's knickers in a knot faster than telling them that, if not for God's sovereign election, they would still be dead in their sins. Brace yourself for some iMonk references and a whole bunch of people telling each other to JUST READ THEIR BIBLES OH MY GOSH.
Anything, absolutely anything, about how wives can help their husbands in the area of faithfulness by, you know, not gradually morphing into shrieking, slovenly, condescending banshees. Write about this one and you'll be moderating the first "What?? You're blaming women for their husbands' infidelity!?!?!1!eleven!!" comment nanoseconds after you hit the publish button.
Mark Driscoll. Just when I think people MUST have figured out that no, Mark Driscoll is most likely not the antichrist, somebody drags up the cussing thing again. From like ten years ago. For which he has publicly repented.
The existence of the charismatic gifts in the church today. Only works if your blog attracts Presbyterians or John MacArthur super-fans -- if you're arguing in favor of charismatic gifts -- because those guys will straight up kneecap you if you defend glossolalia. No lie. Pentecostals are a slightly less formidable enemy in general, if you're taking the cessationist position, but beware of the various "bindings" and "hedgings" they'll try to dish out.
Since I'm sure you're taking notes, one more thing. To maintain just the right level of ire, it helps to have a draconian -- but inconsistently-enforced -- comments moderation policy, and if you can manage to convey a tone of thinly-veiled disgust in the comments sections, so much the better.
Now go have fun out there, kids!