The major exception that most new U.S. travelers to Europe should be aware of is the U.K. It has its own plug, much larger than SCHUKO. You can get an adapter in the States before you leave, but those I've seen in the U.K. are both sturdier and less expensive. They sell them at the airport on arrival (at least if you arrive into Heathrow Terminal 3, which both AA and UA use) or, for less money, at any in-town electrical supplies store, electronics shop, etc.