Campaign Cartographer on my brother's desk. "Yeah, that's very old, another friend also had nostalgia looking at it" he said. It reminded me of long evenings and college sessions drawing all sorts of maps. To use in my games, someday.
Nowadays I don't have the time to draw them. Or don't take the time. Or I grab a historical map.
But, if you want you can also use a random dungeon generator, or a random city mapper. Try the Adventure Generator at Dizzy Dragon for example. It even fills your rooms with encounters according to the game system you choose. Not for Dark Dungeon - but hey, that's not for hack 'n slash anyways.
Or you could go for the map creators at Inkwell. You'll have to fill up their dungeons yourself, but there is also a city map generator, and a mapper for inns. Always good if you want to have a good old saloon fight - and your players insist on having a map.
Or you can just click and click to see what happens next. Click.