Ed - a timely and brilliant question. I would only add that the ideal male Gravatar in the olden days (three days ago), was what I call the "urinal shot". This would be a poorly lit photo of the unclad male torso looking like he is standing before a potty. This kind of photo would give such a man status as a "Torso Dude."
In this new and modern era of total female domination, though, the new photo of choice for all ladies is the "Torso Chick" shot. This is achieved in much the same way, but in keeping with Gravatar's "G" rating. Skin need not show, but you do get bonus points for that. Long T-shirts are perfectly acceptable.
I will prolly continue to annoy all of you with this game until I receive a cease and desist order.
Remember - laughter lowers cortisol.