Balance

Balance refers to the ways in which the elements (lines, shapes, colors, textures, etc.) of a piece are arranged.
[ via About.com: Art History ]

Balancing Act by by theway is a perfect example of balance using asymmetry. When I saw this sketch, I had to comment about the "balance" of the composition... (mostly because I liked the punn on words). Aside from that play on words, I also found the sketch to be rather intriguing: conceptually and elementally.

This sketch by Danny Mansmith also tends to display a nice sense of asymmetrical balance and literal balance.

Although Peter Hart's Giant Tortoise is not 100% symmetrical, it is probably the closest to symmetry that I can find within the Community Sketchbook. Plus, it's a great sketch.

One can also have balance but not necessarily be balanced. Obviously, I didn't find a good example of this, but I thought it seemed peculiar.