Steam Login is a package for Ubuntu and Linux Mint to login into your Steam account directly from the login screen. Steam Login doesn't load a whole desktop environment and since there is no composite manager running you have more resources available to play your Steam games!
To install it first of all you must have installed the Steam client.
Steam Login is available through a PPA for Ubuntu 12.10 Quantal Quetzal and Linux Mint 14. Open a terminal and type:
sudo add-apt-repository ppa:thor27-gmail/steam-desktopsudo apt-get updatesudo apt-get install steam-login
If you are running Ubuntu 12.04 or Linux Mint 13 download the Steam Login deb and install it manually. Be careful, since Steam is now available to all users you don't need the hacked version.
Once installed log out and select Steam in the login screen.