LSrotator - LSRotator lets your iPhone's/iPod's lockscreen rotate according to your device's...
Dreamboard - DreamBoard lets you take control over the homescreen of your jailbroken iPhone.
Cylinder - Sexy homescreen icon animations
Springtomize - Tear down the walls
Five Icon Dock - Tweaks the dock of your jailbroken iPhone so that it can fit five icons instead of four.
Five Icon Switcher - This puts more icons into the iOS4 multitasking bar, instead of the usual four.