I was surfing and came across this video:

http://www.sharpeningsupplies.com/se...one-video.aspx

I found it interesting in that it gives a brief overview of some of the differenet sharpening stones.

They also have a page on the website that goes over the same thing

http://www.sharpeningsupplies.com/sh...materials.aspx

They don't even mention straight razors as this is a sight for woodworking tools and knives but I found the stone descriptions pretty helpful in distinguishing between Norton, Arkansas, DMT, etc.

Take it with a box of salt..