A multi-story trench TDM.
A large, floating island for DM's.
A defend your house (somewhat like Hugums's Defend your Castle, but Zombies come on all four sides and your group of survivors must kill a certain amount to go to the next level. My brother and I made something like this. It's entirely automated, and done with VCE.)
A city/mini-city.
Strange, I just started work on this.
Its FFA, you spawn in five random places on ground floor. Each "level" is 32 bricks, and it alternates, nothing, dirt, nothing, dirt etc. You can fall through the floor onto different layers, and there are velocity pads in select locations where you can quickly jump levels. There are certain build areas, and certain areas where you cannot build (Near the spawns, by the jump pads, and by bridges connecting the top most layer, which is a ton of scattered islands.)