Poser and DAZ 3D are both design packages targeted towards realistic rendering and animation. The idea is to provide the user with pre-designed models and other props you can combine, redesign or adjust to meet your needs. This concept brings realistic rendering within reach for a larger audience, even people with little modeling skills can make a decent looking scenery or create a perfectly fine human character.
And if your tired of the models and props “out of the box” you can extend your options by purchasing additional packages. There’s a whole community around Poser & DAZ 3D who create all kinds of stuff, from hairstyles, to clothing and even complete themed sets are for sale.
It’s not a real surprise that both packages are used to create erotic images and movie clips, remember though that the basic characters don’t have genitals. So if you really want your “virtual sex” to be realistic you will need to buy those separately ( there are some free penises and pubes flying around the web though, google is your friend in this one… ). The ends result of these “virtual sex” projects vary greatly in quality, I guess some artistic skills come in handy here as well.
There are many sites and forums around the erotic side of Poser & Daz 3D, the largest and oldest one is Renderotica. A great place to start and learn the basics ( or just to enjoy the images ). Other sites to mention here are Kaposer.com and Maleposerotica ( don’t forget to grab that free penis for you chars when you there… ). The last site to mention has a more artistic nature, GeoffRidgway.com.