Laws from interesting people has asked a bunch of interesting people to formulate bits of wisdom phrased as "laws" -- they're quite good.
Morgan's Second Law: To a first approximation all appointments are canceled.

Brand's Pace Law: In haste, mistakes cascade. With deliberation, mistakes instruct.

Sterling's Corollary to Clarke's Law: Any sufficiently advanced garbage is indistinguishable from magic.

Link (via Kottke)