Here are some links I've collected for following real world racing:

Twitter accounts tend to link to their official websites.
Series and governing bodies:
https://twitter.com/IMSA
https://twitter.com/FIA
https://twitter.com/F1
https://twitter.com/GP2_Official
https://twitter.com/FIAformulaE
https://twitter.com/indycar
https://twitter.com/indylights
https://twitter.com/UnitedSportsCar
https://twitter.com/FIAWEC
https://twitter.com/EuropeanLMS
https://twitter.com/BlancpainGT
https://twitter.com/24hseries
https://twitter.com/AsianLMS
https://twitter.com/WCRacing
https://twitter.com/gt4cup
https://twitter.com/BritishGT
https://twitter.com/BritcarNews
https://twitter.com/SF_SGT
https://twitter.com/gtmasters
https://twitter.com/GT_Tour
https://twitter.com/GT_Open
https://twitter.com/SupercChallenge
https://twitter.com/dtm
https://twitter.com/FIA_WTCC
https://twitter.com/DunlopBTCC
https://twitter.com/FIA_ETCC
https://twitter.com/v8supercars
https://twitter.com/NASCAR
https://twitter.com/OfficialWRC
https://twitter.com/FIAERC
https://twitter.com/fiaworldrx
https://twitter.com/_TropheeAndros_
https://twitter.com/dakar
https://twitter.com/FormulaDrift

News and broadcasters:

http://www.spotterguides.com/
http://www.radiolemans.com/
http://downforce-radio.co.uk/
http://www.motorsport.com/
http://www.racingcircuits.info
http://racingcalendar.net/
http://sportscar365.com/
https://twitter.com/IMSAradio
https://twitter.com/IMSALive
https://twitter.com/F1onNBCSports
https://twitter.com/IndyCaronNBCSN
https://twitter.com/NASCARONFOX
https://twitter.com/NASCARstats
https://twitter.com/SPEED
https://twitter.com/itvmotorsport
http://www.fanschoice.tv/
http://www.fiawtcc.com/watch-it-on-tv/
http://world-challengetv.com/
http://www.world-challenge.com/liverace/index.html
http://fiaformulae.com/en/live-streaming.aspx
http://www.imsa.com/camera/imsatv
http://www.formula1.com/content/fom-web ... -live.html
http://affiliate.zap2it.com/tvlistings/ ... =nbcsports
http://www.nbcsports.com/tv-listings
http://stream.nbcsports.com/liveextra/
http://www.foxsports.com/tv-listings
http://www.cbssports.com/cbssports
http://espn.go.com/racing/
http://www.mavtv.com/

http://bit.ly/1DBK4da - my Google calendar with racing events and tv times listed

Nice. Thanks for all the helpful abundant links Max.