vertex normal calculation

I am having problems understanding how to convert the math that I find on how to calculate vertex normals. Does anyone have a link to some working code, or something thats easy to follow for the math challenged :)

I am working on some 3D stuff in opengl, and I have most of what I want working, but getting the lights to work will require setting vertex normals, and thats where I get stuck.

http://www.backyardproductions.org/tutorials/tutorial1.asp

Thanks, I will take a look at it tommorow after work.

Hi Chris, thanks for the link it helped a lot. I got face normals working now and I am going to try and work it into vertex normals so that I can do smoothshaded faces as well.