As soon as I got my passport to go to the UK I (because I'm a HUGE Doctor Who geek) purchased a leather cover for it that says "Time Traveler's Passport." There's also a TARDIS imprinted on the front.

My husband is going with me and so I wanted to get him a fun cover for his passport too, something to reflect what he likes. However, all the American based companies sell boring ones that are either blank on the front, or just say "Passport." The only interesting ones I've found are sold in British Pounds.

Conclusion: Americans are boring and stay in the country.