ZCalculator

A fine, visual calculator which works in both dozenal and decimal. Using "A" for ten and "B" for eleven, this calculator includes the basic trigonometric and logarithmic functions, some rudimentary memory functions, and of course the basic functions. It further includes exponential notation and buttons for certain constants (like π). Finally, it allows angular functions to be done using the traditional degree system (260 (360 decimal) degrees to the circle); the radian system; the circle divided into one dozen parts; or the TGM unciaPi system (the semicircle divided into a dozen parts).

Designed to run in Windows, it also runs quite nicely under Unix-like systems using wine.

You can also download it with its C++ source.