Dien,

Great subject...

Think Creatively and Fresh new business ideas will Evolve.

A couple Super Fad resources to Help Get you Started...

Read about Fads from the past 100 years: hula hoops, disco, pet rocks, goldfish swallowing, flagpole sitting, mood rings, Rubik's Cubes, 3D movies, ...
http://www.crazyfads.com/

And Lets not Forget those Bad Fads...
http://www.badfads.com/

Phil