Valve Software's Steam service really needs no introduction--it has been around since 2003 and provides a means for digital distribution, digital rights management (DRM), and facilitates its own gaming community.
CDs and DVDs are now a thing of the past, as Steam offers the latest PC games and plenty of classics. Looking for something the kids would enjoy? Steam has it covered. Want to go retro and play Sega's Altered Beast or Golden Axe? Steam is your time machine to the old-school console hits.
Oh did we mention that Steam has an awesome library of PC games?
Download: Steam V009