If you need more outlets, a power strip will normally be your first choice. What if the only outlet you have available is behind a bookcase or dresser? You can either move your furniture a bit so that it juts out an inch or two and looks a bit “off”, or you can get a flat plug extension cable to put things where they need to be without causing any fuss. However, angling them just right can get to be a bother.
If you need the plug on your extension cable to sit just so, then the 360-Degree Rotating Flat Plug Liberator Cable will be quite helpful. It’s about 18 inches long, and the wall plug is only about half an inch thick. This will be very useful in tight spots, and is cheap at only $5.79. It is definitely situation-specific, but would be worthwhile if the times called for it.
That actually looks useful. They also have 36 and 72 inch versions.
I've asked them whether they do a European model.