It should heat up my living room quickly in winter, something like these electric fan heaters for bathrooms, just bigger and better looking. And it should be portable so I can carry it around to other rooms in my flat. And of course it shouldn't waste too much energy. Anyone having any experience?

Sorry, Webs. I don't know anything about portable heaters currently on the market. But I can heartily recommend a nice hot water bottle. I usually carry them around with me in the winter. I really don't like the cold.

@ amused, thanks for your recommendation. I also don't like the cold. You mean you carry around a hot water bottle in your flat or out on the streets? You must have really big pockets. For how long do they stay warm?

I have a hot water bottle body suit. Everywhere I go, it goes. :) And if you heat the water nice and hot (but not boiling) it'll stay warm for hours.

Get a handwarmer: one of those little velvet covered metal boxes that holds a burning charcoal sticks. Usually on ebay for a few quid. Put that in the pocket of a hoody, and put the hood up. Hey presto! No heating required.