There was a neat idea in chat a few days ago: a few large, central landmasses set in ocean; encompassed around the map borders by an encircling ocean; the ocean running off into the void, so people can "fall off the world" (or, if they're so inclined, build off the edge of the world). Very like the Discworld, in fact.
(The world edge would be at a certain point, the world border would be some distance away, to prevent escape and more land generating).