GIMPshop
Cross Photoshop with GIMP and what do you get?
The answer is GIMPshop! GIMPShop is a fork / hack from the GIMP Project, developed for Mac (but already with ports for Linux and Windows), GIMPShop changes the GIMP UI so that resembles Adobe Photoshop.
[tags]GIMP, GIMPShop, Photoshop, Linux, Mac, Windows[/tags]