Walking through Copenhagen one day last week, my Danish friend pointed out a large and impressive building to me as the headquarters of Denmark's central bank. I mentally did a brief double-take -- isn't there a European central bank that takes care of that? -- before remembering that the coins in my pocket were not euros but Danish kroner, and that Denmark remains outside the eurozone.
The euro has had a bad press lately: economic troubles and subsequent bailouts in Greece, Ireland and Portugal have been widely blamed on the tension between a single monetary policy and divergent fiscal policies. So it's most unlikely that the Danes will be signing up any time soon. (They negotiated an exception to the Masstricht treaty allowing them, like the UK, to remain out indefinitely.)