Artists and art educators:

Robert Ball (painter, printmaker and grandfather!)
The Sarum Studio (academic training in Salisbury, UK)
London Atelier of Representational Art  
Golden Gate Atelier (academic training in San Francisco, USA)
Charles H Cecil Studios (academic training in Florence, Italy)
Royal Birmingham Society of Artists 
Brown Hound (the art and blog of Helen Davison Bradley)
Darren Roussar (online studio and resources for artists)
Artists and Illustrators magazine

Essays and writing on the classical tradition:

The Visual Image: Silence and Slow Time
Tradition in the 21st century
The Sight-Size Portrait Tradition
Slow Painting: A Deliberate Renaissance

Videos and podcasts:

Stan Prokopenko
Drawing Tutorials Online
New Masters Academy

Other websites: 

Making a Mark (online directory for artists from Katherine Tyrell)