AbiSource: http://www.abisource.com/
Wine: http://www.winehq.com/
Gnumeric GNOME Spreadsheet: http://www.gnome.org/gnumeric/
PostScript FAQ: ftp://wilma.cs.brown.edu/pub/comp.lang.postscript/FAQ.txt
Open Source Definition: http://www.opensource.org/osd.html