On one of the rare occasions that I watch commercials, I caught an ad for Post-it Easel Pads last night and immediately thought, “You could totally use those for GMing.”
Along the lines of Post-it sortable cards for GMs (and a host of other office supply fetish material on TT, most of which can be found in the archives under GMing tools), these pads are non-tacky and should stick to most smooth surfaces.
They come in two varieties: easel pads and wall pads. The latter are slightly smaller (20″x23″ vs. 25″x30″), but the whole pad sticks to the wall — draw on the top sheet, tear it off and start over on the next one; the easel pads require an easel, and the individual sheets stick to the wall (they also come gridded, which would be great for maps).
I can see these being very handy if (like me) you don’t have space for a wall-mounted whiteboard, but want some permanency for your in-session scribblings (if you don’t need the permanency, give hand-held dry-erase boards a try), and for conventions or other offsite GMing (student lounge, friend’s house, etc.).