Now that's a calculator

If Apple's simple Dashboard calculator isn't enough for you, check out PCalc. It's a scientific calculator for Mac OS X with support for hexadecimal,
octal and binary calculations, as well as an RPN mode, programmable functions, and an extensive set of unit conversions. There's even an accompanying Dashboard Widget.

If you think PCalc looks familiar, there's good reason. Author James Thompson first wrote PCalc in 1992, and Apple even shipped a special version of the application with some Macs sold in 2002.

PCalc 3 requires Mac OS X 10.4.2 or later and is distributed as a universal binary. PCalc 3 is a free upgrade for registered users who previously bought PCalc 2. A special upgrade price of US $10 is available for those people who had PCalc 2.2.3 included with their Macs.