CHAPEL HILL
Chill Web Co.

CHARLOTTE
Creative Loafing
Music Comet

GREENSBORO
ESP Magazine - only lists the current week's events, but has listings for most of the live music venues in the Triad.
triadcalendar.com - you can search for all current listings. The site is pretty comprehensive for the mainstream live music spots.

RALEIGH
ncmusic.com
raleighmusic.com
Spectator
trianglerock.com

WILMINGTON
The Beat
Encore

STATEWIDE
Carolina Spins - Electronic music listings.

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JamBase.com 
Absolutely the best Jam music listings for the USA. There is usually more jam here than any local NC calendar.

MusicToday.com
The most comprehensive calendar I have found for all styles of music. The only downside is you can only view listings by city.