What are some alternatives?
When comparing Springtomize and Cylinder, you can also consider the following products
Winterboard - Give your iPhone or iPod Touch a graphical overhaul!
IOSLife - IOSLife lets you have animations on your Springboard, Lockscreen, Application Switcher etc.
Muse Art - Muse mission is to transform the lock screen into a tool of discovery and inspiration.
Cydia - An alternative app store for jailbroken devices.
Five Icon Dock - Tweaks the dock of your jailbroken iPhone so that it can fit five icons instead of four.
Pirni Pro - A page about iPhone Software.