[see also: techdoc swiki]

OS X

How to get root access on mac os x
Unix Programming Tutorials
programming on os x keeping potability to linux/bsd: http://www.gnustep.org/
sc3 synthdefs are mach-o bundles

C/Objective-C related:

http://www.gnustep.org/resources/ObjCFun.html
the gnustep wiki
online objective c resources
quicktime api
osc-wrapper by c.ramacrishnan: http://www.mat.ucsb.edu/~c.ramakr/illposed/objcosc.html