WP8 Gaming-On-The-GO is a MUST
A similar peripheral like the Nintendo 3DS Slider Pad Pro for your Windows Phone 8 device.
A pad that has a similar feel to the Xbox 360 controller with a similar button layout.
A pad that has a built-in battery that can power your WP8 while you game on-the-go.
I think a peripheral like this can do wonders to WP8 sales
For example you can take a popular Direct X PC title and easily port it to Windows Phone 8 without having to redesign the game for touch. Imagine playing games like Batman Arkam City or Gears Of War right on your Windows Phone 8 with tactile controllers and without putting a strain to your battery.
Would you buy it and how much would you pay for it?
And better yet any designers willing to take on this challenge. There is a lot of talented Tribe members lets see what you can cook up :)