Autochromatic

Autochromatic is a Photoshop plugin that helps you create duotone, sepia, greyscale and color tint effects.
You can use Autochromatic to add a rust or lavender tone to your image, create psychedelic color effects, or change the foreground and background color of your pictures. Its three color channels help you blend your image with the color scheme of your web page, or create a variety of weird and wonderful color effects that will spark your creativity.