This is excellent value if you haven't picked up Valve's Orange Box yet. You get Portal, Team Fortress 2, and the whole Half-Life 2 collection of gaming brilliance:
The weekend special on Steam is The Orange Box, an award-winning collection of Valve titles including Portal, Team Fortress 2, and the Half-Life 2 family of games. For this weekend only, The Orange Box is being offered at 66% off its regular price to customers worldwide. In the USA for example, the 66% discount means all five games included in Orange are just $9.99. Visit www.steamgames.com for more information.