hardwood floor and speaker

You will usually suffer less damage if you stick spikes in the floor, not the wife.

http://www.taylorsales.com/SuperSpikes.htm

I've used these previously, and they worked great.

I use Lovan footers. They are thinner than many, but are made of hardened steel so seem to hold up fine. I put thin felt under them so I can move the speakers easily. Unfortuntely, they come in a pack of 6 (there stands are often 3 legged), but some places sell them individually.

http://www.lovanusa.com/product_info.php?cPath=26_28&products_id=29&osCsid=a533920c4c854e51cdc5abd861342f0e