Steam Store
The Steam Store is the virtual market place for all games and files released over Steam. Steam games such as Red Orchestra: Ostfront 41-45 or The Ship, and many 250.000+ other games can all be purchased through the Steam Store.
Availablity
The Steam Store can be found within the Steam client itself by click the 'Store' tab when in few view. It can also be found in Steam by clicking here.
The Steam Store is also available through your browser. It can be found here.