A great tweak I discovered five years ago is using artists kneaded erasers instead of blu-tack. One small pad can be sectioned into four pieces, then rolled into small grey booger-like balls and placed under each corner of the monitor. Kneaded erasers will hold the speakers to the stanbds like blu-tack but will clean completely off even after years of being in place. Wonderfully sticky and effective, clean up perfectly, and are cheap, cheap, cheap.
http://www.dickblick.com/zz215/02/
http://www.dickblick.com/zz215/02/