Tension Software has updated Calcine (http://pomola.com/products_calcline/calcline.html), a modern version of the desktop calculator, to version 2.1.1. The upgrade adds new keyboard shortcuts.
Calcline starts as a small window utility. Insert a mathematical expression to evaluate, and the software will do the work.
Calcline costs US$20, and requires Mac OS X 10.5 or later. Version 2.1.1 is a free update for registered users of version 2.x. For new users the cost is US$20. Calcline is an Universal Binary product, so runs natively on both PowerPC and Intel Macs.