The Matrix Cube Clock looks interesting, and despite a unique look it is not difficult to read as some can be. The cubes are connected by a thin ribbon cable, and you are free to stack them at will.
Of course, stacking them in reverse order could make it difficult to read, depending on the time of day. The cubes each measure about 3.5" square, and features 12 or 24 hour format and an alarm with snooze. The clock costs $34.99, and you can find it at Think Geek.
