Claiming a heritage back to the early days of the Nokia 9210 and the dawn of Symbian, and developed by the appropriately ironic 'Burning Platform', Biorhythms Pro does the maths to bring you stats on your current emotional, intellectual and physical states. Apparently. Nicely implemented in Qt though, screens and link below.
Here's Biorhythms Pro in action:
The developer claims that this is the oldest biorhythm calculator on Symbian and he could well be right - there are certainly others in the Nokia Store; (right) setting up a birth date, back in the mists of time....
A neat presentation of the calculated biorhythms, swiping the bottom graph along lets you predict levels on any specific date. Looks like June 19th is a day for me to spend in bed(!)
The 'Interpretation' function provides a plain English expansion of the basic calculations; (right) there's a detailed Help pane, with the background 'theory' of biorhythms and more explanation of what the app attempts to do.