Coolhunting has a sassy little write-up about these comfy seats, worth reading for the idea that they "hug your body like Madonna in a pink leotard." A Belgian product, distribution sites so far only include Europe and Mexico, but the site does not list product pricing or shipping costs. Anyone know of a similar product stateside??
Standard size runs 120 x 45 cm, but you can customize any size you like from the Sit on It company, who also sells non-donut shaped bean seats.
(Thanks, Andy, for the tip!)