What I think Jamie's hair looks like
Someone posted this picture on Diana Gabaldon's Facebook page today. This man's name is Johnny Harrington. He's the closest I've seen yet to my mental image of Jamie's hair color. (Very close to my own, in fact. <g>)
He'd have to lose the beard, though. But I could maybe see him as Jamie in VOYAGER, as Captain Alessandro, and in the scene with Claire in his cabin afterward, explaining in detail what he was planning to do once he got her alone. <g>
I have never seen this man before today, and I know nothing about him. I'm not even sure if he's a model, an actor, or both. A quick Google image search turns up only pics of him with a beard, which is a shame, because I'd really like to see what he looks like clean-shaven. But I like the hair, definitely!
In my opinion, even with the beard, Johnny Harrington resembles the way Jamie is described in the books far more than hunk-du-jour Chris Hemsworth! (No offense to those of you who like Chris Hemsworth, but I happen to agree with Diana Gabaldon about him; his very pronounced widow's peak is a major turn-off for me.)
UPDATE 6/18/2012 6:43 am: I posted this picture on Compuserve last night, and Diana's response was, "Yeah, that's the hair and skin-tone, all right."