I have to say that I am not a Photoshop expert. Occasionally I need to crop and resize images, change the colors, etc. I tried to use Photoshop and found it to be very slow and very expensive. For a long time I was looking for an alternative and yesterday I found Pixel image editor created by Pavel Kanzelsberger.
“Pixel is an RGB, CMYK and HDR image editing, photo retouching and manipulating program available for many operating systems formerly known as Pixel32. It is available for Windows, Linux, Linspire, MacOSX, BeOS, Zeta, QNX, MorphOS, FreeBSD, eComStation, OS/2, SkyOS and even old plain DOS, for both x86 and PowerPC architectures.”
I downloaded Intel Mac OS X version and it works great. It is not Cocoa but neither is Photoshop:
Pixel is a shareware program and currently it is sold for $32 (the price will increase to $79 once the Beta is finished).
See also, Pixel Screenshots and Pixel Artwork.
Update (Nov 7, 2005): TidBITS published Camels and Horses: Alternatives to Photoshop.