Miss Snark is a New York literary agent, whose real identity is often speculated on but never confirmed. She offers bits of insight and wisdom about writing, editors, agents and the publishing world, peppered with references to her dog, Killer Yapp, and the appeal of George Clooney. She's absolutely hilarious, but not for the easily-offended. If you want someone who pats writers on the head and tells all how brilliant we are, Snark Central is NOT the place to go.
Occasionally she does this thing called the CrapoMeter, where she offers writers a chance to submit a hook or query or whatever, and she'll tell you what's wrong with it or why it doesn't work. I've learned a LOT from reading Crapometer entries, beleive me.