Simple offline BC-like calculator for programmers with support for user defined functions and history.
Technetium (Tc) is calculator. It is available in Chrome web store as an Chrome app, which means that you can run it in standalone window and it also works completely offline. It is very similar to BC command line calculator in a sense that there are no buttons (unlike XCalc) but you simply type expression you want to evaluate. Tc use plain JS for evaluation so you can use almost any valid JS code. There are over 60 built in functions, extensive help.
One of the main "selling point" of this app is, that unlike any other calculator app, this one has no buttons. You already has buttons on your keyboard.