Links

Hardware

CP Flight

Engravity

Flight Illusion (Gauges)

Go Flight

Interface Boards

Hagstrom

Phidgets

Active Robots (UK)

EZtronics (NL)

Phidgets (Canada)

Others

Project Magenta

Peter Dowson's FSUIPC

Navigraph

Simparts

Open Cockpits

Boeing 737ng Home build   this is a very good resourse