Depending upon the following choices such as app versus browser delivery and connectivity your options may be limited. Think about the users and goals before making some of these decisions.
Application development?
     Contract
     COTS
     Develop in house
Browser delivery?
Connectivity
     Standalone
          Cable to computer
          SD card
     Connected
          Bluetooth
          Broadband
          Cellular
          Wireless
Delivery and updates
Security
Tracking (SCORM)
Also see Features under Devices.