Here's an interesting article on how to use a BART card to pick MASTER locks. BART is the San Francisco Bay Area's rapid transit system, and the magnetic cards used are similar to many other types of bus and train passes, so a little experimentation may yield some great results.

Yes, I realize I'm posting this secret in an easily accessible section of the Magic Café, but it's a link to a blog post that's already accessible by the general public.