I'm very excited to make the first release of a new project: LBW.
LBW is an ELF binary loader and Linux system call translator for Windows. It allows you to run unmodified Linux applications on top of Windows.
It's currently in a very early stage, and is in no way suitable for doing real work on as it's full of bugs. On the other hand it's adequate for running a Debian chroot, downloading and installing packages with apt and dpkg, compiling and running programs with gcc, connecting to remote servers with ssh, and even running some basic X applications.
Everybody loves screenshots: