iMacs are great, except when you have one sitting with its back to a wall and you need to plug something into the back of it. Particularly with the larger models, you end up having to pick up the iMac and swing it around to get to those ports on the back. Wouldn't it be a lot easier if you could just spin it?
That's the idea behind the Rain Design i360, a turntable that encloses the base of an iMac or Apple Cinema Display, and then allows easy movement of the display. Want to show a co-worker on the "back" side of your iMac something? Just spin the entire computer around. Need to plug or unplug something? No problem -- just swing the iMac or Cinema Display around and do it.
I've had an i360 on my first-generation Intel iMac since just after I bought it, and I can't count the number of times that it has saved me from having to pick up the computer and slide it around to plug something in. I've recommended the i360 to many of my Mac consulting customers who have iMacs or Cinema Displays, and many of them end up buying the device.