AquaTerm is a Mac OS X grahics renderer. It allows command line applications written in ObjC, C, FORTRAN, Lisp, Perl or Python to display vector graphics, text and images using a simple API. Adapters for gnuplot, PGPLOT, and PLplot exists as well.
QuickDicom is an easy to use dicom medical imaging package for Mac OSX, providing QuickLook, Spotlight, Quartz Composer, Window/Level and a dicom file analyzer. Also included is the iiDicom Framework for image/dictionary usage in Objective C and Python.