Cylinder - Sexy homescreen icon animations
Five Icon Dock - Tweaks the dock of your jailbroken iPhone so that it can fit five icons instead of four.
Winterboard - Give your iPhone or iPod Touch a graphical overhaul!
Five Icon Switcher - This puts more icons into the iOS4 multitasking bar, instead of the usual four.
Lockinfo - You can find this app in Cydia - Tweaks.
App Switcher Rotator - This plugin rotates the icons on the iOS4 multitasking bar to the current app's orientation.