Myth Busters are awesome. I try to catch the shows I can. I found the "getting electrocuted from peeing on rail road track thinger" amusing.
And no, you can't get electrocuted. The urine stream breaks up causing it to not be connected. Ha.
As for the credit card thing...
Hotel keys have extremely weak magnetic strips. For reprogramming (as mentioned) and because they get lost or snagged by people. They are cheap. Most cell phones will clear them.
Credit cards are made with very strong strips. It takes a lot to mess them up. Usually they get deactivated because they get worn. Not really from magnets.
I would think a security card would fall somewhere in the middle.
Device: Sprint 8330 Curve - Crimson
My heart belongs to Seattle18 (Who I met on the Forums, ironic.)