Here's a U.S. tipping guide:

http://www.tipping.org/tips/us.html

We were lucky because our German teacher told us before we went to Switzerland that the Swiss don't do tips unless it's truly outstanding, above-and-beyond service for something and then it's just a token amount. I only tipped once I think, when a hotel clerk spent over an hour calling all over Switzerland making me hotel reservations for the rest of our trip (I'd been looking up places the night before on the Internet and reserving then; however, Internet connection was costly, like $30 for 24 hours).