Condensing Your Life on to a USB Flash Drive?

Fear the Clam asks: "My wife and I figure that if we plan for the worst, it'll never happen, so we've been putting together 'If public transportation bites it and we have two minutes to grab our stuff and start walking, never to return to NYC' getaway knapsacks. With luck they'll live in the closet forever. Coincidently, this morning the New York Times has an article about what to take when you have to leave home in a big hurry [DNA verification required], and they suggest making a list of all of things like Social Security and credit card numbers, scanning birth certificates, marriage license and tax returns, and saving it all on a USB flash drive. Since this would be a complete identity kit, encryption is of utmost importance. What's the best solution? A flash drive that claims to encrypt or a platform-independent, self-extracting, encrypted file on a regular drive? Any suggestions for sturdy drives?" Of course, the choice of USB flash drive covers only a part of the problem. What other data would you put on this piece of "contingency hardware", and how would you protect the drive itself in case you did have to "swim for it"?