Here is an interesting visual concept graduation project at the Design Academy Eindhoven. A seat that you don't have to pick up and drag around in a library. Instead, this cute little guy/gal will follow you around like a faithful pet...that you can sit on. ;)
Of course, some of this is made with CG and in some parts you'll see someone moving it, however, if it ever did work imagine the possibility of sitting anywhere you want with a seat in a quite corner of the library or next to the windows as you like. Or, the havoc one can cause by playing around with them!
Hit play or go to the Link [Youtube] - via Freshome.
Here is the concept website by the designer Johann Winfridus (Jelt) van Geest. - Link.
That's what I thought as well about the number of people around. However, if ever built with a smart avoidance system I'm sure it would avoid hitting people.
You'll see at around 1:07 in the right hand corner of the screen you'll see the actors head when he makes the chair "lift up". ;)