Airlines
British Airways http://twitter.com/BritishAirways > On RR's Suck List <
Delta http://twitter.com/deltaairlines > On RR's Suck List <
Jetblue http://twitter.com/JetBlue
Southwest Airlines http://twitter.com/SouthwestAir
Virgin America http://twitter.com/thisishowtofly

Comparison Sites
Cheapflights.co.uk http://twitter.com/Cheapflights_uk 

Cruise Lines
Carnival Cruise Lines http://twitter.com/CarnivalCruise

Destinations
Grouse Mountain Resort, http://twitter.com/grousemountain
Spinn Cafe of Lhasa, Tibet http://twitter.com/spinncafe

Hotels/Resorts
Fairmont Hotels & Resorts http://twitter.com/fairmonthotels
Heavenly Ski Resort (South Lake Tahoe) http://www.twitter.com/skiheavenly
Hilton Disney http://twitter.com/hiltondisney
Luxor Hotel and Casino http://twitter.com/LuxorLV
Mandalay Bay Resort and Casino http://twitter.com/Robert_Hoffmann
Marriott International http://twitter.com/marriottpr
MGM MIRAGE http://twitter.com/VegasConcierge
MGM Grand Hotel and Casino http://twitter.com/Mgmgrand
Myrtle Beach Hotels http://twittercom/mbhotels
Park City Mountain Resort http://www.twitter.com/pcski
Planet Hollywood, Las Vegas http://twitter.com/phVegas
Resideo http://twitter.com/resideo
ResortQuest, International http://Twitter.com/ResortQuest
Treasure Island Hotel and Casino http://twitter.com/VegasDV
Butlins  http://twitter.com/wearebutlins

Publications & Resources
American Automobile Association http://twitter.com/AAAnews
Boingo (Wifi for travelers) http://twitter.com/boingo
Booking Buddy http://twitter.com/BookingBuddy
BrilliantTrips http://twitter.com/BrilliantTrips
Global Base Camps http://twitter.com/GlobalBasecamps
HotelChatter http://twitter.com/HotelChatter
LA Times Travel http://twitter.com/latimestravel
Mahalo Travel http://twitter.com/mahalotravel
Resideo.com http://twitter.com/resideo
Seat Guru http://twitter.com/SeatGuru
Smarter Travel http://twitter.com/SmarterTravel
Travel Rants http://twitter.com/travelrants
UK Travel Weekly: http://twitter.com/twblog  

Recreation
mesurf (Surfing advice & community) http://twitter.com/mesurf
 

Tour Operator
Golf Island http://twitter.com/golfisland,
Onhotels.com http://twitter.com/onhotels
Travel Impressions http://twitter.com/TravelImp
Vacation Deals by Travel Impressions http://twitter.com/vacationdeals
Vallarta-adventures.com http://twitter.com/vallarta_advent

Tourism & Convention Information (AU)
Tourism New South Wales http://twitter.com/sydney_holidays

Tourism & Convention Information (CAN)
Mauricie, Québec, Canada (Tweeting in French) http://twitter.com/mauricie

Tourism & Convention Information (US)
Baltimore, MD http://twitter.com/BaltimoreMD
Bellingham Whatcom County Tourism (WA) http://twitter.com/whatcomcounty
Columbus, OH http://twitter.com/ExpCols
Columbus, SC http://twitter.com/columbiasc
New York, NY http://twitter.com/NewYorkology
Nevada Commission on Tourism http://twitter.com/travelnevada
Orange County Convention Center: http://www.twitter.com/occc
Philadelphia, PA http://twitter.com/uwishunu
Virgina Beach, VA http://twitter.com/VaBeachCVB

Transport
easyBus (UK) http://www.twitter.com/easybus