CrunchBang Linux is a lightweight Debian

Debian

Debian is a computer operating system composed of software packages released as free and open source software primarily under the GNU General Public License along with other free software licenses. Debian GNU/Linux, which includes the GNU OS tools and Linux kernel, is a popular and influential...

 based Linux distribution

Linux distribution

A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications...

, created by Philip Newborough, designed to offer a good balance of speed and functionality.
CrunchBang uses either the Openbox

Openbox

Openbox is a free window manager for the X Window System, licensed under the GNU General Public License. Originally derived from Blackbox 0.65.0 , Openbox has now been totally rewritten in the C programming language and since version 3.0 is not based upon any code from Blackbox.Openbox is designed...

 or the Xfce

Xfce

Xfce is a free software desktop environment for Unix and other Unix-like platforms, such as Linux, Solaris, and BSD – though recent compatibility issues have arisen with regard to BSD Unix platforms...

 window manager with GTK+ applications and is especially suitable for low-end hardware with limited resources (e.g. the ASUS Eee PC

ASUS Eee PC

The Asus Eee PC is a subnotebook/netbook computer line from ASUSTeK Computer Incorporated, and a part of the Asus Eee product family. At the time of its introduction in late 2007, it was noted for its combination of a light weight, Linux operating system, solid-state drive , and relatively low cost...

).

It is provided as an installable Live CD

Live CD

A live CD, live DVD, or live disc is a CD or DVD containing a bootable computer operating system. Live CDs are unique in that they have the ability to run a complete, modern operating system on a computer lacking mutable secondary storage, such as a hard disk drive...

.
CrunchBang Linux currently provides an Openbox and Xfce version for i686, i486, and amd64.