Winterboard - Give your iPhone or iPod Touch a graphical overhaul!
Cylinder - Sexy homescreen icon animations
Lockinfo - You can find this app in Cydia - Tweaks.
Five Icon Dock - Tweaks the dock of your jailbroken iPhone so that it can fit five icons instead of four.
BossPaper - BossPaper is a wallpapers manager for your jailbroken iPhone or iPod Touch that uses very little...
Five Icon Switcher - This puts more icons into the iOS4 multitasking bar, instead of the usual four.