Does anyone know of any self-serve laundromats in Denmark and Norway?
The Rick Steves and Lonely Planet guidebooks gave listing for laundromats in most of the major cities.
Montvask is a chain of laundromats in Copenhagen (and possibly other Danish cities):
Be aware that laundromats here are a bit different - you have to wash, then use the centrifuges to get out extra moisture before drying (washers don't spin as much liquid out). And, at least in the Montvask I've used, all the machines are run from one console at the door. It's a bit confusing, so don't be afraid to ask for help from other people if you can't figure it all out. Took me a few times and some help to get it all straight the first time!
You can probably ask the hotel staff for help. Or stop at any shop and ask one of the locals.