I found this via Thrillist this morning. You'd have to copy down the 4 sets of numbers to keep with you at all times (or, gasp, memorize them), but it actually does work. After about 2 minutes of writing down my numbers, it only took 14 tries to open my gym lock. My skill at legerdemain may not be that of Houdini but I can now bust a basic lock off!
Update: Here's a link to the full size image since the above is a bit small.