An oldie but a classic.
With Portal 2 just released, some of you may want to play the first Portal.
You can buy Portal on Steam for US$9.99 but I found the PS3 Orange Box for ~$15.50 delivered from thehut.com. The 360 Orange Box is about $20 from various sites and the Orange Box on Steam is US$19.99.
Orange Box has 5 games:
Half Life 2
Half Life 2: Episode One
Half Life 2: Episode Two
Team Fortress 2
Portal
Cheers! Just saw the orange box on steam and thought that was a bargain.