Here's a great source for cushion foam, polyester pillow forms, down cushions and custom made outdoor cushions in Sunbrella etc.
using foam for upholstery
DIY Upholstery Supply - this site has tools, materials, supplies & fabric + videos, tips & a Q&A board. Great resource for the furniture DIY'er.
PERFECT foam for dining chairs... High Density Upholstery Foam from Online Fabric Store
FoamTouch Upholstery Foam Medium Density Cushion, 5'' L x 24'' W x 72'' H
A step by step tutorial for a DIY padded headboard created using plywood, upholstery foam, and fabric.
2" x 24" x 54" Upholstery Foam
Demonstration of how to cut upholstery foam with an electric knife.
HR Extra Firm Upholstery Foam Automotive - foam
Round Stool Seat Chair Upholstery Foam Pad Cushion. 16" Diameter By 3" #ImperialAcoustics