Blitz BASIC is still supported but most people now code in C. The old Amiga games were mostly programmed in assembler and most often was used DevPac. But since the AmigaOS is moving to the PPC, this is now obsolete, since coding in assembler on RISC architecture doesn't give you much speed increase, instead of C for example. If you want to code in C you can grab the freeware
vbcc compiler which also allows you to cross compile, i.e. you can make executables for MorphOS, PowerUp, WarpOS, AmigaOS 4 even without having the hardware for these platforms, and as I see despite gcc it's the official compiler of AmigaOS 4 and is included on the prerelease CD. You will need the NDK 3.9 as well, which is available somewhere on the official
Amiga site. Also if you wish to mess with the PPC assembler in the vbcc there is pasm (PowerPC assembler), or you can try
AsmOne. Of course on the Amiga you can program in many other languages like AmigaE, Python, Perl, AREXX, Pascal, AMOS, Modula-2 and even some obsolete ones like Ada, Forth and LISP. Depends on what you want to do, and what mostly interests you in the world of Amiga coding.
For a starter it's suggested to read the autodocs and also there are many tutorial examples and source codes in the
Amiga C Manual and in the
dev/src directory on Aminet.
Have fun.
