PBS
Pbs Teachers: Vanished: Inside the Jet Stream: Giving Rise to the Jet Stream
Explore what generates a jet stream, and discover why they flow from west to east. A link is offered in this site to a helpful animation describing the jet stream process.
National Weather Service
National Weather Service: Jet Stream: The Jet Stream
The concept of jet streams is explained on this site. Read about why jet stream winds blow from west to east, what the polar jet and subtropical jet are, the role that the rotation of the Earth plays, etc.