Apple (AAPL) is said to be in negotiations with Time Warner (TWX) to offer an HBO Go application on Apple TV by mid-2013, according to sources speaking to Bloomberg. The set-top box already carries services from Netflix (NFLX) and Hulu, and the addition of HBO Go could help Apple boost sales of the device. The service allows HBO subscribers to stream original TV shows and movies on the Web and through variety of devices such as Android and iOS smartphones and tablets, TVs, Blu-ray players, Roku boxes and gaming consoles.

Peter Kafka at AllThingsD brought up a good point: why hasn’t Apple opened up its Apple TV platform to everyone? The company’s iPhones and iPads have flourished due to the large selection of third-party apps and games found in the App Store. While the inclusion of an HBO Go app would be nice, the Apple TV needs a full-blown App Store to drive the nail into the coffin of other streaming devices.

Apple TV currently comes preloaded with a total of nine different apps, a paltry number compared to Roku and Google TV.