You will thank yourself if you use levelers, http://www.woodcraft.com/family.aspx?FamilyID=3986
under this. That makes leveling the tank very easy, and not too expensive either. What material are you planning for the stand? If it is plywood, don't forget to get something to cover the raw edges of the plywood.
Levelers. Did not think about them, but sounds like a good idea. I have a question though - I planned for a flat bottom surface to evenly spread the weight. Won't that be redundant if I fix levelers on the 4 bottom corners?
I am planning MDF and then cover it with laminate sheet.