I'd really rather not touch this whole board with a ten foot pole, as I have a feeling that I'll only be adding to a pile of ever growing chaos, but I noticed this one slenderblog hasnt been posted about yet. Not to mention, its one of few blogs I can even bring myself to skim lately.
Essentially, it's a blog written by a professional psychological profiler, and reads a lot like some detective/crime novel. Pretty unique, and being a fan of that genre myself, Its probably most of the reason semi keep up with it.
He's already mentioned several of the other popular blogs around, and I hardcore agony groaned at that, praying for no more tie-ins, but he may drop that, if we're lucky.
It started out on a tumblr:
But he posts actual text blog entries here now: