Wheel Tension Balance Web App by Calvin Jones
A spoke that is looser relative to its neighbors will tend to loosen even more during use, and this will result in the wheel coming out of true. However, spokes that are overly tight can stress the rim, and this can result in a crack at the nipple hole. Wheels with even spoke tension will stay true longer, and as a bonus, your spoke life will be maximized.
Wrench Fu 