thanks for all of the responses.  i read the t.o.s. at deviant art for other reasons last night, and i definitely didn't like the following section

Quote - License To Use Artist Materials. As and when Artist Materials are uploaded to the deviantART Site(s), Artist grants to deviantART a worldwide, royalty-free, non-exclusive license to do the following things during the Term:... the right to sublicense to any other person or company any of the licensed rights in the Artist Materials, or any part of them, subject to the terms and conditions of this Agreement.

i don't believe that this is found in most of the common poser sites (at least, not the ones whose t.o.s. materials i viewed last night).  i know myspace has similar terms.  and personally, while lots of the rights i can see them needing to automatically make thumbnails, to make backups, and other aspects that are basically integral to running a site, i don't see any need for them to be able to sublicense all those rights to another entity. 

but you would suggest watermarking work posted here?  i admit i thought about it, since i already knew this was a  theft hotspot.  but i also don't want to seem presumptuous, and many artists more talented than i don't watermark their work here.  in fact, that includes some who are also denizens of cgsociety and contributors to exotique 2.    so let's turn it around, who has a watermarked works and who doesn't?  and why?

i just want to add that i'm not rabid on this topic.  i understand that the web is a data distribution medium, not a broadcast one.  but as much as i know how fluid information flow is now, i don't want to lose attribution.  i very strongly believe in credit where credit is due, and if people are going to use my work without my name it better be a paid job.