Don't just write up a letter for the sake of it. You won't have any "peace of mind" if it doesn't meet the country's requirements.

Only a few countries require these letters and the few that do, are very picky about what they want it to be and say. Chile, Canada and Mexico come to mind (is Mexico off the list??) Get the latest information. How current should the date be? Should it be notarized? Which language does it have to be in?? Don't write up any letter before getting the facts!

France knows that U.S. passport holders need both parents' signatures so they honor that. No letter (in addition to the permission given when the passport was applied for) needed. I travel in and out of France and Germany and have never been asked for a letter, even before I became a French citizen. I've also taken my children to the U.K. alone twice without problems.

Hopefully, there will be fewer and fewer countries requiring this, since is does absolutely nothing to prevent international abductions.