Picnik is a free photo-edting tool. It has the standard rotate, crop and resize functions, as well as exposure control and color settings. The color settings are basic. You can adjust hue, saturation and contrast in a variety of ways. Although the adjustment is somewhat crude -- and it's unlikely you'll be able to use this interface to 'save' a bad photo the way you might be able to in Photoshop -- you'll definitely be able to make a good photo "pop."