Carrie Underwood, has had a lot of success.
Also cute, also VERY talented -- actually more than Clarkson. MUI she is tearing it up on the CW circuit.
Those 2 are pretty much it for AI -- the rest of the "winners" have done squat. Some of the also-rans have done pretty well, including getting an Oscar, which shows America's teenagers don't generally get it right.
Good Lord, listening to that "Fantasia" is like hearing crystal on a bench grinder.