Numi App - Numi is a beautiful text calculator for Mac.
Qalculate! - Qalculate! is a multiplatform multi-purpose desktop calculator.
ConvertAll - A comprehensive unit conversion program.
SpeQ Mathematics - SpeQ is a small, extensive mathematics program with a simple, intuitive interface.
Calculator++ - Calculator++ is an advanced, modern and easy to use scientific calculator.
NumWorks - The graphing calculator that makes learning math easier.