My wife uses the Tilt'able by Ergonomic Advantage. It is angle-adjustable by putting different feet on the back of the table. This one is made of metal, and has a rubber mat to keep the machine from moving around. She was having neck and back pain after an hour or so of sewing, but she can sew all day with this under the machine! I haven't bought one for my machine because I'm hoping to pick up something less expensive.
http://www.amazon.com/Ergonomic-Adva.../dp/B001839ZKO
Darren