Reminder: Switzerland is not part of the EU (european union)
That's true, but Switzerland is certainly part of the Schengen treaty (http://en.wikipedia.org/wiki/Schengen_Agreement), which regulates border crossing throughout the participating countries (there is no formal border control, between those countries).
Leaving from Zurich to most European destinations by plane I usually don't even need an id.
The UK and Ireland are both outside the Schengen treaty.
When you take the ferry from Britain to Ireland, if I remember rightly, the customs ask you if you are British or Irish. British / Irish citizens don't have to show a passport, but everyone else does. The beautiful thing is that you are just relied upon to tell the truth.
In fact, I have never been asked anyway, they just wave everyone through.
I was really impressed by this story. I never wanted to go the U.S.A. anyway, but my decision is even more strongly reinforced now, I certainly will never go with my children. (Mostly I didn't want to be finger-printed like a common criminal.)
Travelling between the Schengen countries, in my experience, the worst country is Germany, the second worst is Switzerland. Travelling between Spain, France, Italy, Holland, Belgium, Portugal and Austria I don't remember being ever asked even to produce a passport. (In Germany you are though - although Germany is supposed to be a Schengen country, unfortunately the police are still bastards. They make a big rude show of themselves, and like to feel important. We decided after that never to travel through Germany again if possible.)
Also, Australian customs - really friendly. Japanese customs, also nice.
Switzerland abolished border controls (and started issuing Schengen visas) only a few years ago (in 2008 if memory serves). Also, there may be no border control (=they don't check your entry permits if you're coming from a Schengen country), but customs isn't going anywhere.
Leaving from Zurich to most European destinations by plane I usually don't even need an id.