Photoshop is an unquestionably powerful graphic design tool. Plugins like India Ink only serve to enhance your design experience.
India Ink lets you convert your color images to black and white halftones, often giving your images a bit of an old world newspaper feel. In addition, the plugin also has special color modes that produce interesting effects. These effects many parts of an image the effect of having been etched or drawn.
If you're looking for new filter options for Photoshop, India Ink will give your photos a nicely aged appearance.