Flurry is a jailbreak tweak that introduces more control over the appearance of the iOS 7 interface. Options are specifically focused on tint and blur customization. Once installed, the tweak can be configured under Settings -> Flurry.
Besides a toggle to completely enable or disable the tweak, Flurry packs changes that will be applied across the iOS 7 system. Examples include the Control Center, Notification Center, share sheets, passcode entry, and the home screen dock for starters.
When it comes to the settings, each facet of the tweak can be enabled individually, with sliders overriding the defaults. Besides blur and color tint alpha, grayscale tint level and saturation delta factor can be adjusted. There are brief descriptions of each directly in the settings, and changes take effect after tapping the built in Respring button.
Flurry is available from the BigBoss repository on Cydia for free. Jailbreak iOS 7.1.x with Pangu to start customizing iOS. Check here for instructions on how to jailbreak iOS 7.0.x with evasi0n 7. You can also find out how to purchase and install Cydia tweaks with this guide.