SNOT is a building term in LEGO that stands for "Studs Not On Top". It can be a pain to plan, but the results - which hide the brick's trademark studs - are often worth it. Especially when you're building a Star Destroyer that's over two metres long.
This behemoth was put together by Jerac, and while it looks amazing from a distance, it looks even better up close, because the SNOT method makes it look more like a model kit than a LEGO build.
Jerac [Flickr, via Brothers Brick]