"Fortunate Son" was featured in the fourth installment of the Die Hard films. Bruce Willis stars in the films as the American hero, John McClane.
The song also featured in this dramatic film about Steve Prefontaine, who was probably the best American distance runner of the 1970s. Pre, as he was often called, was also quite the dude. Makes sense that they would feature a dude-ish song in a film about a dude-ish dude.
"Fortunate Son" is played during the scene in which Forrest Gump is drafted and sent to fight in Vietnam. It's in Vietnam that Forrest meets Lieutenant Dan, and also where he loses his friend, Bubba. Forrest clearly wasn't a "fortunate son," though he maintains a positive outlook throughout.