I've only seen a few Indian movies, but Slumdog Millionaire is one I won't soon forget. This impressive film features everything from adventure to a love story to deeply disturbing violence. The story of two brothers from the slums of Mumbai is both tragic and uplifting. With masterful cinematography, a great story and talented young actors, this movie won't disappoint.
Another worthwhile offering is The Curious Case of Benjamin Button. It's an unusual story that takes all sorts of unexpected twists and turns. As a writer, I was really impressed with the intricacies of the plot and the use of omniscient point of view in parts of it.
It's unusual lately to find two great movies in theaters at the same time, so take advantage - have a movie date - or two.