This is a fairly simple idea I had the other day. Basically, it's a map split up by a grid of over 600 func_door walls, and each wall is hooked up to a logic_timer with a random value to toggle the walls to raise and lower into the floor.
The result is a large, dynamically shifting maze that works great for Deathmatch, playing with NPCs, and any other uses you can think of for a maze that constantly changes.
It's nothing overly detailed, or exciting looking, but it's still fairly fun to play on.
Here's a highly sped up video showing the walls doing their thing. (This is with host_timescale at 20)
And an older screenshot from inside the maze. Notice the ceiling, you can see it from below, but not from above so the people viewing on the upper floor can see what's going on down below.
I just thought I'd post it here, and see what people thought of the idea. If you have any ideas for additions, go ahead and post them here. I'm already planning to make a room with buttons to disable/enable the walls, and to close/open all the walls in the map.