Macromedia Employee sites:

The best - mostly FlashCom blog is Peldi's:
http://peldi.com/blog

Chris Hock maintains a site that includes a listing of applications built with the Communication Server:
http://www.flashcommunicationserver.net/index.htm
You'll also find a listing of sample applications and applications for sale.

Ryerson University runs a small public development server that includes some articles and tutorials:
http://echo.ryerson.ca

The Flashcomm mailing list (register at http://chattyfig.figleaf.com/) has a wonderful variety of people contributing to it including some of Macromedia's developers. An essential resource! Subscribe to the "FlashComm" list at:
http://chattyfig.figleaf.com/
You can also search the archives at:
http://chattyfig.figleaf.com/search

Stefan Richter has started a popular and lively forum at:
http://flashcomguru.com/
and has posted a variety of tutorials.

Fernando Flórez has posted some improved communication components here:
http://www.funciton.com/commponents/
The components include the most often requested feature from the chattyfig FlashComm mailing list - a PeopleList with icons - but that's not all he did.

Related Technologies

Tom Muck's Flash Remoting, The Definitive Guide companion Web site:
http://flash-remoting.com

Macromedia's Flash Remoting Page:
http://www.macromedia.com/software/flashremoting/
and Devnet page:
http://www.macromedia.com/devnet/mx/flashremoting/

Open Source Remoting Projects:

OpenAMF - Remoting for Java:
http://www.openamf.org/

AMFPHP - Remoting for PHP:
http://www.amfphp.org/

Flash Remoting in Perl:
http://simonf.com/flap/

Carbon Five's FlashGatekeeper:
Essential open source software to secure and control the J2EE and Coldfusion J2EE gateway:
http://www.carbonfive.com/opensource-main-1.html