Anubis-Linux is a distro designed for Linux newbies, system programmers, and computer science enthusiasts. It was originally based on SimplyMepis 8, but now it consists of software mostly from Debian Sid.
AL features:
free documentation to help you learn using and configuring Linux, write software, and more
a lot of low-level system programmer's tools (assemblers, compilers, debuggers) 1*
a selection of pentest tools (Wireshark, Packeth, kismet and many more)
can run many Win32 and DOS programs, and it can compile such programs as well
is easily remasterable, and offers tutorials and tools for homebrew OS development 2*
offers a selection of docs and libraries for game developers (OpenGL, SDL, Allegro)
Debian-based, and uses customised 2.6.31 kernel to support Sqlzma compression
uses KDE 3.5.10 as Desktop Environment (love it or hate it, I love it)
1*) C(++) and Assembly. if you need Java or C# capability you'll have to install extra software
2*) current 64-bit version may, or may not successfully compile 32-bit operating system code