When you run a low prep or improv game you can never have enough maps. Thats not technically true, there are those who literally fly by the seat of their imaginary pants but me - I like a bit of paper to spark and idea from mid flow. Im also a big fan of creating a resource I can use again and again in different ways.
I've been doodling maps in a little gridded pocket book during lunch breaks, I got a couple of them from the work stationary cupboard - but i'll pick up a Moleskine when I fill them up. I don't spend long on each drawing either, just quick - and I'm not really sweating the finer points of the maps, I just start doodling.
I've been doing it for a week or so - i've now got a enough random maps, should I ever need one on the fly, i'm covered.
Check this afternoons 10 minute doodle :