I have a passport-sized pouch which straps to my thigh. Put jeans on over that, and the passport is going nowhere. But I only use this if I don't trust the environment in which I'm traveling.

The inside jacket pocket is not necessarily a good idea -- an acquaintance of mine had his jacket completely ripped off by thugs in Buenos Aires a few years ago. But it's still where I usually keep a passport while traveling around Asia.