I agree with whoever said Christina Aguilera has talent. She has a really good, strong voice. But her image... ICK! Too bad.\
From American Idol (the second one, I didn't watch the first one), Clay Aiken is definately talented. I almost fell off the couch the first time I heard him sing! Same with Ruben and the really skinny girl who sang that Whitney Houston song.
Here's who else I think has a lot of talent:
Norah Jones (I can't wait to see how her second album turns out)
Vanessa Carlton
Alison Krauss (she has one of the most beautiful voices I've heard)
Alice Peacock
Gwen Stefani (the rate this girl changes her style is amazing, 'cause she manages to stay good!)
John Mayer
the guys from Jimmy Eat World
And there are a few more that I can't think of right now...