Ok, so I'm trying to prepare myself in case I have to live under a box someday with only my razors to my name :D ... (I have been hunting for work, but that's a side note).
So I've been experimenting with minimalist approaches to shaving for fun lately. So today I shaved with a palm stropped John Engstrom (4 shaves in, still going strong) and nothing but water on my face.
I basically washed my face and wet a rag with lukewarm water. When the water started drying out, I'd wet my face with the rag and go back to shaving.
It worked out pretty well. The shave was close, and got the job done. It was not as good as with soap in terms of comfort or end results, but it give a passable shave. You need to be careful about pressure though, or else I'd suspect you'd have a bit of burn.
Anyway, I have my zombie defense plan in place, my tinfoil hat, and my stock of twinkies... I should be ready for the apocalypse. :)