On its own, Activator is probably one of the most useful jailbreak tweaks available. It allows you to map practically any button or touch gesture to an iOS action. But what makes it really cool is that devs can create their own tweaks to extend its capabilities.
And that's the case with this next package, by developer rjharris. It's call App Activate, and it enables you to initiate any of Activator's actions by double tapping an app icon . So for instance, you could set it so that double tapping the Music icon starts playing music...