CandyBar allows you to change the system icons in Mac OS X that you normally can't, including including the trash can, volumes, default folder, and more!
CandyBar 3 also now includes a full-featured icon organizer (formerly called Pixadex) that acts like an iPhoto for your icons: collect and store your icons in the same application you use to change them!
Of course, there's more: CandyBar also now lets you customize the look of Leopard's dock. Too shiny? Too flashy? Make it look the way you want by simply dragging images in to replace. Nice.
Will 512 x 512 icon support, improved iContainers, a smooth new interface, Quick Look integration, and much more, Candybar 3 is to icons what air is to, uh, living.