Oil Filter Magnets!
There seem to be many types. Wrap around models, ones you drop inside the filter cartridge, and some that are electrified(!).
Here are a few for consideration:
http://www.ridermagazine.com/output.cfm?id=1743715 http://www.shopfiltermag.com/
Also, don't forget the old oil pan drain plug magnets.
Again, as always, your personal choice to use, agree with... or not. Seems that it can't hurt (one perspective), and the concept at least seems interesting.
Ride Safe (and without metal dust in your oil!)
Bob