Bluetooth OnOff launched last night and enables the toggling of Bluetooth with just a tap -- or even, via a blank toggle, simply by launching the app. To do this, head to the app’s settings panel in Settings and toggle the unlabeled switch there, kill the app through the multitasking tray and relaunch it.
It's a universal app, for iPhone and iPad -- however, this sort of direct control of Bluetooth is prohibited by Apple's iOS app guidelines and it's unclear how long Apple will allow the app to remain on the App Store.
Bluetooth OnOff is $0.99 on the App Store. [Direct Link]