Like many city dwellers, I'm forced to do some serious furniture multi-tasking in my small apartment. My dining table doubles as a desk, which requires lots of paper shuffling at mealtimes. My modern, bentwood dining chairs are great for dinner, but they're murder on my back for any real length of time, making it hard to do any work. Since storing a separate, more comfortable desk chair defeats the point of space saving in the first place, I've found some attachable lumbar supports that will help my posture, but can be removed when I want the dining area to look more elegant and less like a decrepit hunchback lives there.
Because they're portable, these pillows can also be transferred to the car for long drives, or anywhere else you want to feel really old. Warning: these pillows are not sexy and all the models selling them are pushing 70, but since I want my spine to last until I'm 70, it's probably worth feeling a bit uncool.