Idea for Apple iOS, or any mobile operating system for that matter.

The ability to have dynamic screens: you could bring all applications with notifications to the forefront. You could bring the applications with the most usage time to the forefront. You could put data hogging applications on a secondary screen to keep data usage down. You could bring certain types of applications to the forefront automatically, based off what is happening to the user: if GPS detects travel, bring transit, mapping and directions apps to the forefront. If a user enters a mall, bring shopping apps to the forefront. If a user makes a phone call, bring social media apps to the forefront. The options are endless. The result is a user who spends less time accessing relevant applications.