Here are some great software for vacations or business trips:

City Guides:

Lonely Planet guides to New Orleans,Miami,New York,LA,Chicago,Hong Kong,Las Vegas,San Francisco,Sydney,Paris
http://www.citysync.com/

Palm Tours of Ireland
http://homepage.eircom.net/~palmtours/

Various City Guides
http://www.aramis-inc.com/


Country Faqs:

http://www.aramis-inc.com/Pages/Products/intltraveler.htm
http://www.worldfaq.com/index.jhtml
http://www.geocities.com/SiliconValley/Peaks/9768/Pilot.html

Lists holidays for tons of countries
http://www.atc-info.com/DO/index.html

Other:

Really cool map showing real-time day and night map of earth.
http://www.codecity.com.au/

A bunch of apps: currency calculator, Paris guide, country plug types
http://www.wizu.com/index.html

Subway guides for almost every city
http://home.worldnet.fr/~patriceb/Technique/Metro/Metro-en.html

Display numerous time zones, convert clothing sizes and currency
http://www.mobimate.com/worldmate/index.html

Language conversion
http://www.palmix.itil.com/