This is not an exhaustive list. These individuals or companies are considered trend-setters, early adopters and thought leaders in their space.

What other Twitter accounts and serious players in category “Internet Marketing” do you think should be followed or at least considered? And, how do you determine their authority and quality (to be added to the list)? Hat tip to Rich Page for seeding the list.

Andy Beal (Marketing Pilgrim)
http://twitter.com/andybeal

Seth Godin
http://twitter.com/SethGodin

Search Engine Roundtable
http://twitter.com/seroundtable

Rand Fishkin (SEO Moz)
http://twitter.com/randfish

Mike Buonomo
http://twitter.com/SearchBuzz

Search Marketing Gurus
http://twitter.com/smgurus

Fumi Mastubara
http://twitter.com/newmediazoo

Copy Blogger
http://twitter.com/copyblogger

Eric Friedman
https://twitter.com/EricFriedman

Danny Sullivan
http://twitter.com/dannysullivan

Duct Tape Marketing
https://twitter.com/ducttape

Barry Welford
https://twitter.com/BWelford

Search Engine Guide
http://twitter.com/SEGuide

Craig Ritchie
https://twitter.com/craigritchie

Doug Hudiburg
https://twitter.com/dhudiburg

Gator Herb (Marketing Sherpa)
https://twitter.com/gatorherb

The Product Guy
https://twitter.com/theproductguy

Search Marketing Gurus
http://twitter.com/storyspinner

DJ Francis
http://twitter.com/DJFrancis

Newspaper Girl
http://twitter.com/NewspaperGrl