Once I saw it was possible to have my phone control which armor or weapons I am using my mind went crazy with ideas and here are my two favorite that depending on the system I would like to attempt to make or have someone else make them.
1.) Finally put my secondary monitors to use. It would be amazing to have a large Map with live data show on one of my secondary screens. Assuming this is something we could view on the iOS means it might be possible to use the same technology to have the game talk to your PC to display a live map!
2.)This one is a lot more robust and came to me when I was walking my dog. I thought it would be cool if we could track how many steps you take and when playing fallout have it get that data. Then based on the data the game would give you a very small amount of experience or be rewarded you with weapons or armor. You could even make it so based on the amount of steps you took you would increase your chances of getting better and rarer loot.
While those are some ideas I thought were cool.