What is a good base for speakers


Fussing with setting up a new system in basement. My vintage ADS L710's sit on original stands that don't have fittings for spikes. As the stands sit on a carpeted floor, they rock a lot (no pun intended). I'm thinking of some sort of base to settle them down. Looking for suggestions of a material appropriate for stability  - any experience with wood butcher block, granite or slate cutting boards as a base? More DIY than expensive. Thanks for any suggestions. 
mcondo
+1 for Millercarbon, he is correct about springs.  I tried stone, spikes, no spikes, Herbbie's gliders and the Townshend podiums sound the best.  Get the cheap spring option he mentions and try them out
I made speaker stands out of Red Mahogany wood. I added damped casters so that I can move them easily to get the best placement. I spent far too much time on the finish but they look nice and serve the purpose. They will raise the height of drivers, so that must be taken into consideration with placement. I took much time to decide if I could get good sound after they were raised and that was crucial.