Great summary by Cougar.
I'll add that I've been leaving my edges coarser and coarser. As Cougar said, coarse edges slice better, polished edges shave and push-cut better. I find I make slicing cuts much more than push-cuts, so a coarse edge is really nice. I recommend everyone try this in their garage to really convince themselves that it's true. Sharpen a knife and polish it, then try to take a couple slices of very hard poly rope. Now take a few strokes on a coarse hone to rough up the edge, and re-try the test. The difference in performance should be very noticeable.
One trick I often do these days is polish the entire edge, then rough up the back part, from about the handle until the beginning of the belly. That way I have a polished tip & belly for push-cutting like opening mail, and the rest of the edge is coarse for slicing.
Oh yah, you asked for specific grits. For polishing, I'll typically go to a spyderco fine stone, then strop. Occasionally, I'll go to a DMT x-fine hone in between, for the super mirror polish. For a coarse utility edge, I leave the edge at the coarseness of the Spyderco brown (what do they call it? medium?) stones, or the DMT coarse (blue) stone.
Joe
[This message has been edited by Joe Talmadge (edited 29 September 1999).]