iOS (Jailbroken): One of the frustrations that comes with multitasking in iOS is that you can only see the first few apps in the drawer. Often you want to quit an app that hasn't been used in a while, and so you're stuck scrolling around until you find it. MultiStory seeks to remedy this problem by doubling the size of the multitasking drawer, allowing you to see more apps at a time.
On top of that, it provides enhanced music controls too. All you have to do is download the tweak from Cydia, restart Springboard, and you'll see a double-sized multitasking drawer. It will also place your music controls and volume slider in a single section, rather than two, which is nice (even if it looks a little weird). MultiStorey works on pretty much any jailbroken iDevice with multitasking capabilities.