Dungeon curves. The other day I was staring at a page of my own designs in the Inked Adventures Basic Pack (Modular cut-up sections etc) and I couldn't quite picture how some of the curved sections actually worked. Also I'm not great at providing working examples, or photos of their use in play. -Not that I need an excuse to play with figures and floor plans. ;) Also, a little known secret to cardboard and paper plans is that they be steadied or prepped on cork boards with pins. Modular dungeon sections seem to be anachronism in an age where even the most "old school" of dungeon masters like to have a prepared as a single poster created in a graphics or virtual tabletop app.
Inked Adventures Basic Pack http://goo.gl/0k4XzD
Minis/figures: Wizards of the Coast
Corkboard 30x40cm and pins from Wilko's (UK)
Inked Adventures main site: http://inkedadventures.com/main