http://www.youtube.com/watch?v=iRt5qagkGBU
Remember webOS? Say what you will about Palm, but the HP-acquired firm has pioneered what's arguably the most efficient implementation of multitasking on a mobile device to this date (no jailbreak required, of course). For those not in the know, the webOS multitasking metaphor is a stack of cards which represents your running tasks.
Each card can be moved around, dismissed and manipulated with a flick of your finger. It's a remarkably fun and engaging solution to efficiently interact with your apps, one which gets the job done while moving out of the way. Designer Jesse Head took that idea and applied it to the problematic iOS multitasking tray, replacing the boring grid of icons with app tiles sporting nearly full-screen live previews. It appears as useful as it's gorgeous to look at, no?