iOS (Jailbroken): Since the iPhone homescreen is essentially an app launcher on its own you might not think it needed much in the way of quick access. Deck is a simple but well-made side bar launch tool that adds easy access to a number of customisable apps and settings.
You can access Deck in a number of customisable ways, but the simplest is to swipe to the left on the top of the screen to pull up the launcher. By default, you have access to the music player, Siri, camera, and you can compose tweets. Other options include customisable apps, settings toggles and more. It's one of the nicer-looking jailbroken tools out there, and it works just as described. It's handy if you prefer having the toggles for settings like aeroplane mode and Bluetooth easily accesible, but don't want to clutter up your homescreen or notification centre with icons. Deck is $US1.99 and you can find it in the Modmyi repository in Cydia.