While Steam Linux Client is still being in development, there is an excellent digital game distribution service Desura available for the Linux gamers. Desura has been released for Linux one year ago and has even been open-sourced this year.
The game list of the service is huge and growing very quickly. Here are some of the latest Linux games on Desura:
Freespace 2: Space combat simulation
Majesty Gold: The next game from Linux Game Publishing
Earthworm Jim 1 & 2: Yet another platformer
Descent 1 & 2: A classic 3D first-person shooter from Interplay
Swords & Soldiers: 2D slidescrolling real-time strategy