There's also some hostels outside the U.S. that will charge you in U.S. dollars when you check in and pay with a U.S. credit card. I've had this happen twice in Ireland. They also use a conversion rate which is marked up a few percent. The last time this happened I had them reverse the charge and send it through again in euros.

One of the hostels in Dublin told me they had no control over how the billing was done, and being that I was using a U.S. credit card their software was set up to bill me in dollars and they could not change that. I got in the habit of asking what currency I would be billed in before presenting my credit card.