GENERAL DIRECTORY:

Effects:

Amplifiers:

Tube Amplifier

Pickups:

Guitar Pickup Tone Database

BUILDING YOUR OWN EFFECTS (links by mcconnachiea):

Kits:

http://www.buildyourownclone.com

Parts:

http://www.tonepad.com (PCBs only)

http://www.circuitspecialists.com (the CSI-STATION1A is a $100 Hakko soldering station for $40)

Misc/Info:

http://www.geofex.com

European sites:

http://www.banzaieffects.com