*Currency: Currency converter with downloadable daily updates.
Developer page: Henrique Martins & Braunstein

CurrencyX: Currency converter with downloadable daily updates.
Developer page: Armando Neves

KMaps: An application that lets Treo (and connected Tungsten users)users use Google Maps.
Developer page: ULocate*

Métro: PDA guide to worldwide public transportation systems.  Listings for almost 200 cities are available.
Developer page: Patrice Bernard & Frank Van Caenegem

Travel Organizer: An application to help the traveler track flights, accomodation, car rental and milage info, packing checklists and itinerary packing.
available at: PalmSource

*Vindigo: Vindigo for your PDA (Palm and Pocket PC/Windows Mobile) knows about every great restaurant, bar, store, and museum in major U.S. cities. Learn about every movie and live music show playing, and find ATMs and parking lots nearby. Requires annual subscription for content updates.
Developer page: Vindigo

*X-Man: Manhattan street address locator.
Developer page: The Roaming Empire

Zagat To Go:  Zagat Survey ratings and rankings for over 24,000 restaurants and nightspots in 70+ cities.
Developer page: Handmark