The Steamwire Quiktool is a comprehensive measurement converter. It contains over 1000 measurement units in 30 different categories. The built in expression evaluator allows you to enter equations as well as values for conversion. Quiktool also includes a calculator which harnesses the same expression evaluator to calculate in real time as you type in your equation.
Quiktool's scribble pad lets you create a quick note or sketch, save it, and recall it later. It's like having a sticky note on your desktop for things you need to jot down quickly and remember later.