As a DM, the #1 tool on my wishlist is a world generator like donjon's, but zoomable (ala google maps) with reasonable procedural generation at levels down to a few meters.
I recognize that this is a significantly challenging task, but hey, if Dwarf Fortress can do it...
This is something I did for our DnD group, the map was created collectively in a photo editing tool and then split up with MapTiler (https://www.maptiler.com/) which generates HTML/CSS/JS you can throw up on a server I have here: http://maps.opendnd.org/ao/. The main issues I found are some skewing from the original map and some pretty bad pixelation when you get to some of the lower levels. That could all be remedied with a better vector graphic for the map -- something to work on in the future.
Wow this is something I never realized I wanted until now. Seems like it could be a cool hackathon project, plus getting to learn more details about how google maps / bing maps / openstreetmap do their zooming.
I’ve played with a bare OSM server before to try and get an osm based map working. Ends up you just have to scrub all the existing geometry and draw it from scratch, but it’s so-able. Worst problem I had was trying to generate realistic height map bit maps.
This looks very cool! But I noticed something odd: I generated several cities of various sizes and almost every city block is marked as "craftsmen". This can't be right...
The other similar resource I know about is the ancient In the Labyrinth manual for Steve Jackson's The Fantasy Trip.[1]
[1] Jackson recently got back the copyrights for The Fantasy Trip and they have a kickstarter going on now for newly-reissued (and updated, I think) copies.
If you’re into this stuff -this one does cities (make your own Skara Brae): http://fantasycities.watabou.ru
This is one of the Big Dogs: http://donjon.bin.sh/
It does worlds, dungeons, monsters (for different editions of the game), quests, and a ton of other stuff.