Just playing around in photoshop tonight.
Have one of these in the critique section but I thought I would see what effects I could come up with for a High key portrait and a low key one.

Here are my attempts.

[KrisK10D]

I think each technique works well with the expression of it's subject. But I' like the low-key shot very much.

[LaRee]

You've brought out the eyes in both with your post processing which is important with portrait images. I really love the low key image.

I already said I liked the Low Key in your other thread.
I really like the High Key also but I think you overdid the PP just a tiny, tiny bit with the eyes, nose and mouth. To me it has a kind of 3d effect, the facial features seem to 'jut' out from the rest of the picture because the graduation is too steep.
Don't get me wrong, I think it's a great picture (far better than anything I could come up with at the moment) but try dialing it back a notch or two and I think it could be even better.
Cheers, Gary