Here's a full-featured scientific calculator for your iPhone or iPod touch. It's really six calculators in one, with new button sets exposed by a tap on the tab bar.
Features are important, but it's the little things that count, right? Little things like a design that looks like it belongs on your iPhone; big, easy to press buttons; a delete key in case you hit the wrong one; and picking up right where you left off if you are interrupted by a phone call--even in the middle of entering a number.
1. Algebraic entry
2. Scientific calculations
3. Conversions for
4. Logic calculator supporting base 2, 8, 10 and 16
5. 10 memory registers
6. Numbers range from about 1e-313 to 1e308
7. Displays 14 significant digits