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.
Infiniboard - Vertically scroll your home screen pages!
SwitcherMod - SwitcherMod lets you customize the iOS4 multitasking bar.
Infinidock - Infinidock is the ultimate dock customization tool for jailbroken iOS devices.