Tools

Essentials:

XCode
On your OS X Install disc or may be downloaded from Apple Developer Connection Site, IDE, API Documentations and a lot of tools.

Darwin Ports
not a reversing tool per see but install a BSD like port system, enabling you to compile a lot of *nix applications from a repository. Works like a charm under MacIntel.


Disassemblers:

otool
Apple's objdump equivalent, already installed on your Mac (or installed by XCode).

otx
otool's bastard son, great disassembler, open source.

otoole
Ehnancer for otool's output.

class-dump
not a disassembler, dump classes and other as Obj-C structure.

Machonist
As for now only a PPC disassembler (may be compared to w32dasm), on its way to be opensourced, and who knows, extended to support x86 code...


HexEditors:

0xED
Suavetech's hexadecimal editor, freeware.

HexFiend
Open Source, BSD like licensed hexeditor.

hte
a bit like hiew (I miss you) but missing assembly edit feature. Need to be compiled from source.


Text Editors:

TextEdit
Installed on your Mac, painful to use with big file (allocate all file in memory).

SubEthaEdit
Handles big files well, nice collaborative feature too, trial version downloadable.

TextWrangler
little free brother of the excellent BBEdit which is commercial _and_ expensive...


Debuggers:

gdb
the GNU debugger, installed as part of XCode, powerful but miss some features when you've grown with SoftIce.


Compilers:

gcc
the GNU compiler, installed by XCode. Compiler for C, C++, Objective C and more. Yes, used by Apple to compile OS X binaries.

NASM
The Netwide x86 Assembler, should be installed with Darwin Ports with a sudo port install nasm.