PostScript
Crowd-sourced documentation and tutorials by the Cocoa developer community
High quality, device independent graphic display language and the industry-standard printing and imaging technology from Adobe.
http://www.adobe.com/products/postscript/main.html
The original NeXT system used DisplayPostScript (DPS), providing all of the power of PostScript, but for interactive display. In the OldDays, you could upload PostScript code into the DPS system.
PostScript Applications
HyperJeff's OS X Links, search for PostScript http://osx.hyperjeff.net/Apps/
GhostScript http://www.cs.wisc.edu/~ghost/
MacGhostView http://www.kiffe.com/macghostview.html
TeXShop (uses GhostScript) http://www.uoregon.edu/~koch/texshop/texshop.html
