Hi, can somebody help me what software to use to create 3d naked (sex) characters? I just need something simple, I want to create just a very small characters, not big ones.

daz3d and poser are the only 2 i know off.

I suggest looking in the "workshop of creators" section there is a good thread there for graphics.

http://the-new-lagoon.com/viewtopic.php?f=30&t=3716
http://the-new-lagoon.com/viewtopic.php?f=30&t=3682

Has anyone ever tried 3DS Max? It costs 1400 Dollar and is even used in the professionel branch. With 3DS Max you can create everything from scratch but it takes some time if you´re a beginner. If you´re a student than it´s completely free for you. But Daz3d would be the option for you. I think it´s the easiest to learn.

I think I've seen games using Sims figures, and 3DSexVilla figures. I don't know what the actual process used to make them was, though.

Make Human.
http://www.makehuman.org/
you may use Daz3d characters too, but you need a license to use the 3d meshes in your 3d game.
If you want to build a 3d character from scratch, then use blender, 3dmax (expensive), maya (super expensive). I have 3dmax which I used with Skyrim modding. I would say it's not that easy to make a 3d character. judging by the way you asked the question, I presume you don't even have basic skills to use a software like 3dmax, so I strongly suggest to go for a software like Make Human or daz. both are free. they provide a framework, and you can build your character on it.