Clark University
Clark University: Dave's Short Trig Course: Applications of Trigonometry
This Clark University site gives a brief historical perspective into how trigonometry is used in astronomy, geography, engineering, physics, and mathematics.
NASA
Nasa: What Is Trigometry Good For?
This site from NASA is for anyone who has ever asked "Why do I need to know this," this is a must read for you. It documents historical uses of trigonometry.