Used to carry a Spyderco with moderate regularity years ago. I've retired to just a Swiss Key. It does just about everything I need it to in a pinch. Don't have to worry about any sort of security issues either. It's innocuous.
http://www.swisstechtools.com/produc...D=VZ75GDTdP68A
And yes, it has a tiny blade, so it could be considered a pocket knife? :]