My pocket sized A-Z for London. It lives in my pocket when I spend time there.
Cost me about 5 pounds 5 years ago.
Also my cellini travel wallet. It was a gift from my aunt about 10 years ago - cost about 99 rand. It however always has my FF card, my year long A+ travel insurance, my O/S bankcard, my passport and my accupressure chart for jet lag. Its got a hand strap and it fits very neatly into my travel hand bag.
As for locks and the TSA - the TSA approved locks are good - have about 4 of them and have yet to have any problems with them (though I have yet to travel to the states with them ;-) ).
Also labels with addresses so that I can send postcards.