What Tools/Networks Do You Recommend For New Teachers?

For teachers new to online networks/web2.0 tools, what do you recommend for immediate and ongoing Professional Learning. I am deliberately avoiding the term Personal Learning Network -PLN- as I think it is a mistake and does NOT help our cause in redefining Professional Development in the digital age. 
The terms 'Social' and 'Personal' are problematic in my view.

I'm looking, specifically, for sites useful to PE, Music, Art and SPED teachers....for their own learning and that of their students. These will be used in a workshop I will be leading. 

NETWORKS
Classroom 2.0
Fireside Learning
Linked In
The Educator’s PLN

BOOKMARKING
Del.ici.ous
Diigo

MICOBLOGGING
Twitter