Clash of Clans
Amazon Instant Video (I have started a petition on change.org, asking them to develop one)
Update for Waze (Same as above, but I don't think it's ever going to happen)
Update for Instagram, Vine and Twitter
Toyota Entune and Lexus Enform (or any other car apps that work with your car)
Tiny Wings (even though it's REALLY old)
A better TripAdvisor app
Traffic Rush by Donut Games
Obviously I don't need all of these, but if these developers were to support WP, I think a lot more people would consider switching.