Kotatsu: The excellent Japanese cozy table, with built-in blanket and heating element. It keeps your legs warm while you sit under it. It's pretty much the best thing ever during cold Tohoku winters in poorly-insulated apartments with no central heating.
I've wanted one ever since I moved back to the USA, but importing one costs $500. Then Sushu proposed making our own, and it turned out to be cheap and easy.
Step 1. Get a cheap square coffee table from Ikea.
Step 2. Buy the "Cozy Legs Flat Panel Heater" from Amazon.
Step 3. Buy 4 angle brackets (1.5"x5/8") and some wood (1"x.5"x4 ft) from the local hardware store.
Step 4. Use wood and angle brackets to secure heater panel to the underside of the table.
Step 5. Put a blanket over the top.
Step 6. Put something flat on top of the blanket to hold it in place and provide a suitable writing/drawing surface. Or, if you don't have a suitable surface, put whatever you have lying around, like some cardboard and a mirror.
Finally, make sure to get some legless chairs for lower-back support so you don't mess up your spine sitting under this thing for hours at a time.
(Proper Citation: Sushu already explained most of this in her comment on this post)