Software: Debian Testing + some Unstable packages for various things (libdispatch/Grand Central Dispatch aww fuck yeah. Also, multi-arch fat binaries). GCC 4.6 and Clang/LLVM SVN trunk snapshots, CGDB for debugging, Tundra and autoconf for build automation and configuration, Notepad++ under Wine for editing (I consider it an improved Gedit/Scite). Sometimes I'll use emacs or vi, but prefer the simplicity of notepad++. Terminal shell and shell/python scripts for project management. Git or mercurial for SCM/dVCS.
Also got a Windows gaming desktop rig with MSVS 2010 on it that I occasionally use, but I usually do my development work on GNU/Linux.