(Returning to Shakytown! Kristin gets into a pillow-fight mood for her 2nd post. Comment away.)
Pillows dont have to be square. They can be tubular. They can be round, rectangular, oval, spherical, stellar or pyramidical. For all these shapes, Down Etc. is a comprehensive resource for pillow inserts. They also have a full line of bedding in copious sizes and shapes ($4.50-$300.00).
All of this is very inspirational for a d.i.y. or custom made project. Im planning a big, round, banded, linen floor cushion like the one above from Tricia Guild of Kings Road, London. You can call with measurements from an existing cushion cover and theyre likely to have it. They do not do custom sizes (for custom, try cushionworks).










I really like Tricia Guild/Designers Guild, too. Good luck with the DIY project.