Virtual Printers For Electronic Publishing (eg standard Web banner sizes, and OS X standard Icon/Button size):
The Page Setup below shows use of the 128x128 Icon size for drawing a photo-realistic icon suitable for OS X's Dock.  The screen shot shows the designer is using Points for the scale, and has the rulers enabled.  The stepper control in the ruler's upper left corner allows quick changing of the tick mark intervals on the rulers.

Export to the ICNS format
Export full icon families in the Mac ICNS format.  These may be installed as OS X badges or icons for files and folders.  The family of images provide optimum icon quality for all necessary display sizes. 

Professional Color Gradients (using OS X's advanced image compositing capability):
The gradient fill palette is shown lower right.  There are many geometries available, (spot, egg, conical, oriented, positioned,...) gradients.  The gradient for the tablets shinny surface is a Highlight Composite (14 different composite algorithms available-Source Over, Highlight, XOR, Plus Darker, ...).  Of course you can use transparency with the gradient colors.