Me personally, I'd like to see some maps based off video games.
For one, maybe someone could turn the Subspace Adventure Mode map in SSB Brawl into a playable map?
Or a map of the worlds in Kingdom Hearts? Of course, I'm not sure if playing it would be very fun, but it would be fun to see nonetheless.
More fun maps would be based off the Final Fantasy series? There's so many series, I'm sure that several maps could be based off that. I know right away that the Tactics series (I've only played Advance on GBA and War of the Lions on PSP) could be turned into a map. And for FF12, each new "area" you enter (not counting homes inside cities), can be made into a territory, making the entire map ideal for quadruples.
I don't really know too much about Halo, but seeing as it's so popular, I'm sure lots of people would enjoy playing on such a map.
How exactly would you go about making a map anyway? Maybe if I learned I could try some by myself...