There are a few ways to do this.
NifSkope (link) targetted mainly to cryengine based games
3D Ripper DX – http://www.deep-shadows.com/hax/3DRipperDX.htm
This program works with Direct X 8 and works extremely well with Emulators like Dolphin which is a emulator for Wii and Gamecube games. There are also Emulators for the first XBOX which this program also works with as long as you have Direct X 8 you can use this program it will not work with newer versions of Direct X.
3D VIA Printscreen – http://www.3dvia.com/products/3dvia-printscreen/
This program works the same way as 3D Ripper DX except for that it does’nt matter what version of Direct X you use. I am still learning with this program so I will teach here as I learn myself.
A Video On How To Rip Models –
http://www.youtube.com/watch?v=yL2eejJoWI8