Android only: The unlock and sound sliders on Android are handy, but if you'd like quick access to other things from the lock screen, WidgetLocker willl let you add anything from widgets to app shortcuts to extra sliders.
WidgetLocker is a pretty neat app, replacing your normal Android lock screen with one you customise. You can add any shortcut or widget you want, as well as other sliders that adjust things like brightness, ringer type or launch other applications on your phone. It's got a ton of other cool features too, like hiding the notification bar on the lock screen, using a different wallpaper for the lock screen and more. It's definitely worth checking out if you'd like to eke a bit more functionality out of your phone without having to unlock it every time.