Runtime DNA - Absolutely the top of the line for Poser props, textures, characters, clothing, scenes - a lot for sale and a lot for free.  If you're looking for high quality - here's the place to go!
 

3dpmr - Lots of terrific stuff at great prices.
 

PoserTrax - Just what the banner says! Store, articles & a rather large list of freebies.
 

Gypsy Camp Graphics - Free tubes, textures, wallpaper and more! Go check out the free stuff - you know you want to.

Render Spice - Fantastic new Poser resource for some excellent characters, sets, hair, props & more - this promises to be one of *the* places to check out when you need to add that spice!
 

Planet Vixens - Home of Baron Vlad Harkonnen's excellent Poser works. Visit BVH today and fill up your runtime with outstanding quality clothing & more for your Poser renders.