USG
http://www.usgdesignstudio.com
Donn steel, aluminum, and stainless steel grid systems, Drywall suspension system flat, curved or domed.

Keel Manufacturing
http://www.keelmfg.com
FRP, severe environments.

Gordon
http://www.gordongrid.com
Steel & aluminum, drywall.

Lindner
http://us.lindner.ag/Home_us.Lindner
Modular, curved, custom.