Left thumb on top.
Right handed, right eye dominant (though as I'm a bit short sighted in my left eye there's not much incentive to deliberately use it).
I think I'm generally right side dominant, anyway, though I can use my left ok.
As for the dancer, I can choose which way she's turning, I don't think I really have a preference. Looking at the picture too long makes me feel a bit queasy though. For the first few seconds it looks like just a flat two dimensional shape with no obvious perspective; I have to concentrate on which way I want it to go to actually see it properly.
I have done some tests on brain side; from what I remember there wasn't much in it, or the results varied.
I hope everyone's remembering that the left side of the brain controls the right side of the body and vice versa, by the way. I just thought I'd mention it, as some commenters seem to be thinking it's the other way around. Dominant left brain may imply dominant right hand, and vice versa, though with motor skills I don't think it's so clear cut.
Freude, schöner Götterfunken Tochter aus Elysium, Wir betreten feuertrunken, Himmlische, dein Heiligtum! Deine Zauber binden wieder Was die Mode streng geteilt; Alle Menschen werden Brüder, Wo dein sanfter Flügel weilt.
I put my left thumb on top, I'm right handed... this might have to do with the thumb ring I wear on my left hand though
according to this test in this thread I'm pretty severely right brained- this is because I'm disorganized, impulsive and not inclined to care for what authority figures have to say... I kind of liked the split used in that thread where IxxJ was associated with left brained (my ISTJ is pretty far left brained!) and ExxP was most associated with right brained (I tested pretty severely right brained)
Human beings make life so interesting. Do you know that in a universe so full of wonders, they have managed to invent boredom? -Terry Pratchett