GalliumOS is a fast and lightweight Linux distro for ChromeOS devices.
Linux can run many different types of applicatons. No matter what you're trying to do, an application exists for Linux. ChromeOS is very limited. Sure, NaCl (Native Client) brings the ability to run native code to ChromeOS, but that's a hack at best, and there's still no good software to take advantage of it. With Linux you can install any Linux compatible software, totally natively. Firefox, Transmission (BitTorrent), LibreOffice, Steam, VLC Media Player, Kodi Media Center, the GIMP, VirtualBox, and many more are available on Linux to do things that simply aren't possible on ChromeOS.
Why GalliumOS as opposed to other Linux distros?
Optimizations that eliminate system stalls and improve overall responsiveness
Integrated ChromeOS mouse driver provides a touchpad experience similar to ChromeOS
Built on Xubuntu
A fast, lightweight, beautiful, and fully functional desktop
For the issues that affect ChromeOS devices and are not found in standard distros