Meet you at the corner.
Ah what a delightful little joke. Doesn't really apply, as this post is going to be about ceilings, painted ceilings particularly, but hey, they're all part of room architecture, right? This is the reverse of normal paint location, which is on the walls, but I'm really liking the effect it creates. You could go with all one color,
a subtle pattern,
a color with a drop-down onto the wall (this one is my favorite),
or you could go all out and have a version of the actual sky above your head. Bringing the outdoors in, in a virtual sense.
(photos collected from pinterest, mila-loveology, and googleimages)