hardwood floors and spikes

I agree about the brass footers. Just make sure they are sized for your speakers (larger diameter for larger speakers) to avoid leaving indentations on the floor. Old hardwood flooring is much harder than newer hardwood flooring made from faster growing trees -- you may not have an issue with size if your house is older. There are many sources for these footers. They are normally 1.5 to 2.5 inches wide and about .25 inches high and they should have a dimple in them to accommodate the spike. Good luck. If you need to get some great sources, let me know and I'll look up the folks who sold me mine.

Pennies work well. After time they do require replacement. The first time around I chamfered the pennies with a drill but now I just set the spikes in the center of the Lincoln Memorial. For extra thickness spring for nickels.

I have found the brass Audio Points and Coupling Disks sound great and protect my wooden floor.
http://www.audiopoints.com/

Linn "Skeets"

I use Nordost power points in titanium.
Not cheap but quite effective and virtually invisible