GIMPshop
Modification of the graphics program GIMP to replicate Photoshop feel
...It shares all GIMP's advantages, including the long feature list and customisability, while addressing some common criticisms regarding the program's interface: GIMPshop modifies the menu structure to closely match Photoshop's, adjusts the program's terminology to match Adobe's, and, in the Windows version, uses a plugin called 'Deweirdifier' to combine the application's numerous windows in a similar manner to the MDI system used by most Windows graphics packages. While GIMPshop does not support Photoshop plugins, all GIMP's own plugins, filters, brushes, etc. remain available