Thank you all for your contributions.

"The only way to tell that would be to use the "who's online" feature and click on each name individually and see if they have a gallery." 
"Everyone who registers has a gallery.  However, not everyone uploads to it. "
"an empty gallery is like an empty can of whipped cream" 
"But I'm a programmer, and if I had access to your database, I could answer this question in 30 seconds. " 

Yes, this is why I thought the question could be better answered by a moderator.  Not having a moderator is like having an empty can of whipped cream.

"I have a gallery" 
"I have a gallery too." 

And God bless you both for providing them! The world would be a lesser place without them. 

And you, Acadia, are the jewel in this forum's crown.  Your newbie greeting posts are the most first-class things of their kind I have ever seen, anywhere. 

" the image uploads are in the 100's per day just in the Poser Gallery alone."

Thank you, oh full can of whipped cream, for that datum.  [ florishes one hand in a courtly bow.] 

Even without adding in the other galleries uploads, 100 or so Poser uploads a day seems a little lop-sided, given an average of  4,000 or so people on line at any given moment.. 

What got me thinking about this is that I had a Renderosity member (not myself, I swear) make me his or her favorite artist.   To verify  this wonderful person's good taste, I clicked on his or her homepage and found no uploads there at all.  Strictly a viewer and a not a doer.  So now I'm starting to think that, with our wishlists out  and a what appears to be an actual audience, we who upload are sort like street corner muscians with our carrying cases open.  Not a bad gig actually.