From NCH Software:
PhotoPad Free Photo Editing Software for Mac OS X. Retouch photos quickly and easily and edit and apply effects to photos and other images. Crop, rotate, resize and add effects like sepia tones, greyscale and red eye reduction as well as adjusting the hue, saturation, brightness, contrast and more. Crop, rotate, resize, and flip pictures. Touch up photos to remove blemishes and red-eye.
Apply effects such as oil paint, cartoon, sepia, and more! Adjust image color, hue, brightness and contrast. Fast and easy. Load gif, jpg, psd, png, bmp picture formats and more. Preview effects before applying. Easily delete any applied effect without removing other effects. PhotoPad can be added to your right click menu for easy access.