CompanyNewsletters.com 
Large collection of articles on how to write and produce company newsletters, whether a traditional printed or online version.
http://companynewsletters.com/index.htmlThe Cluetrain Manifesto 
A strongly reasoned plea for corporate communicators to speak with a human voice.
http://www.cluetrain.com
International Association of Business Communicators. 
A worldwide learning community for professionals committed to improving the effectiveness of organizations through strategic communication. Articles, conferences, career opportunities.
http://www.iabc.com
The Editorial Eye 
Dozens of articles relevant to corporate editors and writers. Topics include today's usage dilemmas, style sheets, trademark controversies, web editing, estimating editorial jobs, and software.
http://www.eeicommunications.com/eye/
Ivy Sea Online 
A wide range of free articles on communication within and from an organization. Organizational communication articles and tips.
http://www.ivysea.com/pages/a_and_t.html
360° Newsletter - Jack Morton Worldwide 
Bimonthly newsletter about branding, marketing, and corporate communications.
http://www.jackmorton.com/360/frontpage/default.asp
Put It In Writing 
Writing company business newsletters.
http://www.put-it-in-writing.com/
Melcrum 
Global research and training for internal communicators.
http://www.melcrum.com/