From one of my favorite photography sites, DPReview, and a list of apps that edit photos that are also not Photoshop.
None of these applications is a true one-to-one ‘replacement’ for Photoshop CS6, particularly if you’re a graphic designer or video professional. But for the rest of us – people that just want to retouch images, manipulate composition, adjust colors and saturation, apply canned filters and effects, and remove that kid who wandered into the foreground of an otherwise-perfect photo – they may prove to be very useful.
Adobe Photoshop Elements and Lightroom make the list, as does Apple’s Aperture. Oh, and Pixelmator.