MarginMaster is a Business Calculator that will help you figure out Markups, Profit Margins and Break-even points.
BMI is a tool to find out if you are in the healthy range of weight compared to your height.
For the electronic hobbiest. It's a calculator, a reference tool all in one. Resistor will determine the value of an electronic resistor and Ohm's Law is a Ohm's Law calculator. Very useful for those little electronic projects.