What 'til you see this thing. Craziness, I tell you! James at Brothercake has created a 3D dungeon model through clever manipulation of CSS and the DOM. It even has correct shading - done on the fly! - to effectively convey perspective.

How did he do it? The solution builds off of Tantek Çelik's Study of Regular Polygons (which is fascinating in its own right), adding some Javascript to accomplish the shading. Check out the examples at Brothercake and appreciate CSS borders in a way you never thought possible. (You can even navigate through the CSS-based underworld!)