James Thomson, the author of DragThing, releases the version 3 of PCalc, his calculator application. It's been completely rewritten to take advantage of Tiger (even comes with a Dashboard widget), it's quite gorgeous, and it does everything you'd expect from a scientific calculator (and even some more):
It is a fully featured 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.
Great app! Congrats, James!