For emergency scenarios, I'd think a phone number and your name (no address) would be all you'd need.
The phone number should be someone who probably won't be travelling with you, but that can keep
a copy of all the information you'd want a doctor or lawyer to have. The idea being that if someone
finds the name and number, hopefully they'll call the number and give the name. :-) You're still
vulnerable to social engineering attacks, but much less so than if you also include, say, an address.
Make the person who's calling give a callback number if you want.

The rest of the stuff... I've memorized mine. SSN, credit card number, etc. Not on purpose, really.
I just use the data so often it's burned in. :-)

If you want to carry the info in a form that's useful to you, but mostly unavailable to others, you
might store it in your cell phone or mp3 player.

Consider hiding the paper with sensitive information in your shoe or some other location likely
to remain attached to you.

Record the information as a message on your answering machine. If you need it, play it
back from any phone on the planet. This works best if you can control your machine from
a touch tone phone and it has some sort of passcode.

Make a web page with the information, but don't link to it from any other web page. No
search engine will find it. If you need it, manually enter the URL from any browser on the planet.

Data doesn't have to be with you to be available to you.