Man, the 70s were chock full o' excellent films.  From "MASH" to "One Flew Over the Cuckoo's Nest," "Network," "Nashville," "Days of Heaven" and especially "Taxi Driver," the 1976 Martin Scorsese-directed grungy, street-level study of alienation.  Robert De Niro, memorable as the young Don Corleone in the second "Godfather" movie, brings us into the closing decades of the 20th century as Travis Bickle, the obscure and troubled cabbie.  This remains one of his signature portrayals.