If Doctor Spock had a Palm device then the chances are that a scientific calculator would be one of the first things he'd want to install. One highly logical solution for him is Unit Converter & Sci-Calculator, which includes an algebraic calculator, a unit converter, a periodic table of elements and a listing of physical constants.
The algebraic calculator includes all the functions needed to solve basic math operations. In other words, addition, subtraction, multiplication, division, percentages, exponents, square roots, and so on. All the buttons are clearly laid out and calculations are performed instantly.
On the other hand you have an amazing unit converter, acccessible from the same user environment. It's incredibly well organised and features over 3,000 different conversion factors, sorted into 95 different categories, which are in turn split into further sub-categories. There are lots of categories that you'll probably never use, but luckily you can customise them yourself, so can clean them up a bit.
The app also includes a periodic table and a list of 308 physical constants. This data includes information such as acceleration due to gravity, the speed of light and Avogadro number. All this is perfect if you're planning to charter the SS Enterprise and go when no man's gone before, but for mere mortals much of this information will be meaningless.
If you work or study in the field of science or mathematics then this is a very useful addition to your software arsenal.