When Dad starting programming for the Mac it was in MacPascal (one quarter of freshman physics lab), then in Rascal  (on which he later worked), then LightSpeed Pascal (which became Think Pascal), and then Think C (previously LightSpeed C), and so on. 
However, when we were writing a Mac application back then we just needed to know one language (Pascal or C) and maybe some 68xxx assembler for interpreting what Macsbug was telling us (if writing low level code). We did have to learn the Macintosh Toolbox which is equivalent to the class libraries of today (e.g., Cocoa) – Dad still has 2 feet of shelf space devoted to “Inside Macintosh” books from that era that probably should be recycled already :-).
In contrast, Dad is close to finishing an iPhone app for a client that displays data from a database on a server (and some live XML data feeds from the server). To complete this project has required:
So, the point is, Wow! The breadth of knowledge that is required to create the software we create today is astounding compared to what it was back when this adventure started 25 years ago.
Not the new Rascal languages (rascal-lang or the Rascal DSL meta programming language), the old one (dare I say original one 🙂) which was the first (or one of the first) native IDEs that would let you program the Mac in something other than assembly language without a Lisa (see 1985 entry at old one, but it was in development before then I believe).
For the history nuts, my older-than-40-memory says my complete sequence on the Mac was roughly: MacPascal, Rascal, Consulair C, LightSpeed Pascal, Think Pascal, Think C, Think C++ (TCL – Think Class Libraries), MPW Objective Pascal (MacApp) & C++, Metrowerks CodeWarrior C/C++ (PowerPlant), Xcode C (Carbon) and Objective C (Cocoa) and now on the iPhone Xcode Objective C (Cocoa Touch).
Some of the relevant history is here (Dad was there from 1984-1990 and hanging out and eventually working in the “DLab” from sometime in late 1985 or early 1986 onward). The rest is work related from 1990 onwards.
Lots of other side languages for learning, fun and contracts over the years, some on the Mac, some not: Basic & Pascal (high school, before Mac), 68k assembler (MacAsm originally), 8051 assembler, Java, Smalltalk, Lisp, Eiffel, Visual Basic, Visual C++, whatever PocketPC required (straight C? can’t remember), and so on. What a strange soup of names. What’s it all mean? ha!