I've read some really good stuff in the past week, and just in case you missed it:
Monsters and Manuals goes into player-character information disparity. When the player knows stuff the character doesn't. My basic take is to conceal as much as I can from the players that their characters wouldn't know. I go as far as to tell folks to roll but not why, or roll without telling them why (or sometimes even really checking the results - it's either a fake-out, or just I fidget by rolling dice.) I love those moments when the players - utterly unaware of approaching danger, or lacking some piece of critical information - react as if they knew it was there all along. Those times they walk right up to the one 10x10 wall section with a secret door and open it, check the ceiling on the only room with slime monsters lurking, or only move that one statue that conceals treasure. And I hate watching the contortions players make when they know bad stuff is going to happen to their PCs and now they feel a need to change their actions to appear to not cheat by being ready for it. Plus, personally, I find real surprise is a lot more fun than pretending to be surprised.
The Dragon's Flagon covers one of my favorite bits about B/X D&D - the attribute bonuses. 9-12 is average, and 13+ gets you some kind of bonus. That and the bonuses being pretty flat (+1 to +3) and standardized. You don't need a crazily-exceptional character just to get anywhere, like in AD&D, and stats matter a lot, unlike how OD&D appears to work (where bonuses are stat and class specific, and some stats seem to do nothing.)
Russ Nicholson posted a "short" post of pictures, including this gem:
Beedo cranked out a hell (ha, ha) of a megadungeon concept - the God of Death's mountain of challenge, basically. He sits there hoping for heroes to come and die, and stocks it full of monsters, traps, and challenges to do them in and gold to lure them in. It's better than my bs concept, that's for sure.
Finally, check out this excellent advice for a new GM over at Tower of the Archmage. It pretty much nails it - have fun, relax, don't worry, don't over-prepare. I have played with a new GM who was so worried that he had every mini he could need, book to cover places we could eventually go, and rules nailed down that the game crawled and rarely ran. Which is too bad, because we were all willing to just let anything go as long as we got to roll dice. It's easy to forget as a GM that your players will be pretty forgiving if you just keep the game moving and give them chances to do fun stuff.
(I forgot to link these two, initially - so I'm fixing it now)
Also check out Hack N Slash on player agency, defined. It's a good, technical look at what "player agency" means, and I think it is worth reading before attempting to discuss the subject.
And read Gaming Ballistic's explanation of how to do The Black Widow vs. Mooks in one of the Iron Man movies. With the right power level of character and the right settings of the dials, the detail-heavy Technical Grappling turns into glass-smooth mook destruction and badassery. Doug has a tendency to post awesome stuff and then bury it with an admin post shortly after, so you might not have noticed this.