Piano Technicians Guild - use this to find piano tuners/technicians in your area; also has other general information about pianos and piano technology.
Music Teachers National Association - if are looking for a piano teacher but do not know whom to ask, this is about as good a place as any to look for a piano teacher in your area.
Piano World and
Piano World Forums - discuss all things piano with people who are interested in piano.
PianoSupplies.com - for piano accesory and parts (metronomes, piano lamps, piano polish, tools, etc.).