John2e
Headphoneus Supremus
Ultrasone - After dealing with them, the idiots at McDonald's seem like brain surgeons
Blue Jean Audio
TTVJ (I buy from Todd pretty often despite his prices being generally a bit higher than competitors)
Schiit and Woo Audio: Made in the USA headphone amplifiers by nice people at great prices.
Head-Direct: Fang is a very nice person to deal with.
Ray Samuels: His products may be on the expensive side, but he's a very nice guy with very good products.
Beezar: TomB is just awesome.
Edit: D'oh! I just realized this was a bump of a thread I posted in back in March.
Also, hopefully I can soon add JH Audio to this list. Brittany was very helpful at the NY meet.