Well imagine that...

http://www.quantcast.com/

Found some pretty interesting info here (and all of it save for CP and r'otica seems to be just base estimates):

daz3d.com pulls in ~31,000 unique visitors a month US-only stats; 11% passers-by, 47% regulars, the rest "addicts" (as a percentage of all visits, not just uniques)

renderosity.com pulls in ~30k uniques a month US-only stats; 9% passers-by, 33% regulars, and the rest "addicts" (ditto )

contentparadise.com? here's the surprise*: ~112k uniques a month globally,  31% passers-by, 52% regulars, and 18% "addicts" (again, ditto)

• If Poser 5/6/7 pings CP whenever it starts or whenever the "Content" tab is opened and there's a clear Internet connection (which is likely - I can't remember offhand if it does or not), then the results are liable to be skewed here.

renderotica.com pulls in ~15,800 uniques per month; 11% passers-by, 32% regulars, and 57% "addicts"

Now for the low-end:

runtimedna.com gets ~4700 uniques a month (US-only); 13% passers-by, 87% regulars. No addicts here.

3dcommune.com grabs ~5100 uniques per month; same stats as RDNA.

raunchyminds.com gets less than 2,000 uniques a month (not sure how much less); 48% passers-by, the rest regulars.

3duniverse.co.za gets less than 2000 as well... not sure what percentage are regulars, newbies, etc.

Kinda interesting overall...

/P