VPO related links

VPO software

GrandOrgue
Genpo
JOrgan

Samplesets (free)

List of samplesets on GrandOrgues Sourceforge page
Jeux d'orgues
Appletonaudio (also has free software for Noise Reduction and Looping of samples)

DIY related links

Vidar Fagerjord's webpage
Raphi Giangiulio's Homemade Pipe Organ (check especially under "Construction")

MIDI hardware

Midi Gadgets Boutique