Here are my favorite iPhone apps:

SBB Timetable: Train, Tram, Bus schedules, great!
AP Mobile News: World News on your iPhone
Fring: MSN, Skype, GTalk all in one app
Express: Your daily horoscope
FlyCast: Thousands of radio stations, works with Wi-Fi connection
Currency: Great to convert CHF to $, euros and many other currencies
Live Poker: Play online FREE, lots of fun.