The Actors Key (ActorsKey.com) - offers classes and workshops with casting directors. They are unique because they give you a scene ahead of time and you get to work one on one with a reader.
Casting About (CastingAbout.com) - online searchable database for Los Angeles casting directors and other industry data. Updated daily.
Craig Campobasso (CraigCampobasso.com) - Craig is a casting director and acting coach who is also a long-time friend of mine. He has a series of on-camera acting classes that are invaluable!
CrossFit (crossfit.com) - great site for workout tips. Check out their "workout of the day."
Internet Movie Database (IMDB.com) - one stop shopping for all industry related data. Upgrade to an IMDB Pro account for access to contact information for virtually anyone in the entertainment industry.
Krav Maga Worldwide (kragmaga.com) - Israeli self defense system which I trained in (and have a black belt) for over 13 years. Krav Maga has many screen credits including "Batman Begins", "Terminator 3" and "The Departed."
Screen Actors Guild (SAG.org)- In addition to normal guild services, SAG has a foundation that has many free services and workshops.
Spotlight PR (SpotlightPRCompany.com) - referred by Dallas Travers, this is an a-la-carte PR company that provides various PR services without having to pay a monthly retainer.