Cydia - An alternative app store for jailbroken devices.
Springtomize - Tear down the walls
Zestia - Zestia is a mobile app designed to assist you in organizing your hectic schedule, social life, and professional persona.
Winterboard - Give your iPhone or iPod Touch a graphical overhaul!
JazzMyApp - Let JazzMyApp surprise you with amazing apps everyday. Try it out yourself.
Dreamboard - DreamBoard lets you take control over the homescreen of your jailbroken iPhone.