The speedo needle is attached to a metal cup.  The end of the speedo 
cable has a magnet on it.  The rotating magnet attracts the metal cup 
and attempts to rotate it, but is resisted by a spring.  Assuming 
that the speedo cable is working, remove & disassemble the speedo and 
use a lightweight oil (sewing machine) and lube the center shaft.  
You can check the cable by disconnecting it and go for a drive.  
Reach over you dash, pick it up and it the shaft will be rotating if not 
broken.

- Jeff

- - - - - - - - - - - - - 
Todd,  you wrote:

<< I was driving at lunch and noticed that the speedometer had stopped
working.  Speed was stuck at 0...when I was driving home to work,
surprize! The speedo was working!...Do I have speedometer gremlins? Or am
I just going crazy and imagining that
the speedo was not working.

   This happens on my van all the time.  When I notice it happening,
I just give the console a whack on the left side and it begins to
register speed again.