Jailbreaking your iOS device allows you to modify your lock screen, home screen and even the appearance of your apps and how they are arranged. WinterBoard is a popular tool that allows you to alter the look of your device by downloading themes to your iPhone from Cydia. There are themes to change everything, including your lock screen slider, your iPhone keypad and even your Wi-Fi icon. WinterBoard offers so many more possibilities than just downloading drab wallpapers.
CustomSiriBackground lets you spice up Siri's boring look by giving her the background of your choice. There are also several WinterBoard themes which can change Siri's icon into something more fun. My favorite is Siri9000, which transforms Siri into HAL 9000 from the film 2001: A Space Odyssey. You can even change the Siri start up sound into a few Hal quotes with a little advanced jailbreaking know-how.
Like WinterBoard, the jailbreak tweak Zeppelin allows you to download different carrier icons to replace the carrier logo on the top of your iOS Device. Once installed go to Settings > Zeppelin > Theme and choose the Zeppelin icon you wish to use. It's really that simple. Zeppelin comes with its own stock icons, or you can download individual icons, or packages, like the Zeppelin Super Set, to add to your choices.All the tweaks and themes listed above are free to download from Cydia, however, some themes and Zeppelin packs do cost money to use.