Besides of sticking just a piece of paper onto a metal surface you can use this simple trick to expand the possibilities of your magnets...
Step 1: Parts List
All you need is a (powerful) magnet, one of these fancy desktop cable holders and a blob of strong adhesive... Or a multiple of these ingredients.
Step 2: Prepare
Remove the adhesive foil from the bottom side of the cable holder. Maybe it's necessary to clean and/or roughen both surfaces of the two parts with solvent and/or sandpaper.
Step 3: Bonding
Make sure that the adhesive is suitable for the job and the glue the cable holder on top of the magnet... Et voilà!