I have been thinking about this lately as well since my new SW 10" Goto Dob arrived today
The concrete pad out the back I use to observe from has less than a 5 degree slope but will be enough to upset accurate goto's I guess. I was looking to manufacture a solution and found these:
http://www.opticsmart.com/accessorie...elescopes.html
At the best part of $100 delivered, I think I will still try to make something myself, but it is something to go off. Edit: Doesn't look like they deliver to Oz anyway but it still is a nice idea
cheers