I'm thinking of launching a service similar to usertesting.com or trymyui for mobile website and apps.
Developers submit their app or website along with testing scenarios. Scenarios would be something like "You want to book a hotel room for next weekend at Waikiki"
Testers go through the scenarios while narrating their actions and thoughts. For example "Ok, so I'm going to enter 'Waikiki' in the search box and tap the search button".
The result would be a video of the phone screen, with the audio of the tester speaking.
Developers, designers, what else would you need from such a service?