These work very well when stacked interlocked between your shelf or floor and your power cord...they're rubber so they don't mark anything up either...
http://www.audiogon.com/cgi-bin/cls.pl?accstwek&1239231445&/Blueharmony-Cablock-cable-isol
http://www.audiogon.com/cgi-bin/cls.pl?accstwek&1239231445&/Blueharmony-Cablock-cable-isol