Both of my trekking poles have button compasses on the wrist strap. I also have a Suunto mini compass/thermometer zipper pull on my lanyard. Then I have my regular compass. THEN I usually stash a magnet compass around somewhere (a little oblong neodymium magnet which will always point north/south on a flat surface).

And all that is generally backup for my GPS (both my Garmin and the one in my blackberry).

Sure it's redundant but until button compasses weigh 3 lbs a piece, I'm just fine with so much overkill.