SleepFX is a cool tweak for the iDevice. It is one of those tweaks that you don't come around a lot, like Gridlock and Barrel, the smallest change to your device can have a exciting outcome. With SleepFX, whenever you lock/sleep your device, you can have it do an effect/transition before the screen shuts off. There are several transitions to choose from, so if you're bored of one, you can choose another. Though the tweak does come at a steep price of $4.99, it adds a unique look to your device and will have people asking. Check out SleepFX in the Cydia Store.