Microsoft
This is the main MS site for Project 2007. It offers free discussion groups, comprehensive PM resources, templates, and an online magazine (e-zine).

The Free Management Library
Free non-profit clearinghouse of management info and resources, with an excellent collection of PM materials.

Commercial Solutions Reading Room
Free collection of PM info, resources, and links.

4pm
For-profit training, but offers extensive free resources and info.

PMFORUM
The site states that “The mission of the PMFORUM is to use the Internet to provide an economical forum for the promotion and exchange of project management information and knowledge worldwide.”

Projectmanagement.com
According to the site, “Projectmanagement.com is devoted to providing project managers in the construction, finance and IT industries”

Michael Greer's Project Management Resources
For-profit training and consulting, but really excellent collection of free resources and dedicated to educating new project managers.

The Project Management Center
For-profit training, but offers extensive free resources and info.

Computer World
IT mainstream magazine with numerous free articles about PM.

gantthead.com
Online community for IT project managers offers resources and expertise.

StarWright
A free reference site for the information needs of project managers.

OpenWorkBench
The site states that “Open Workbench is an open source desktop application that provides robust project scheduling and management functionality. Already the scheduling standard for more than 100,000 project managers worldwide, Open Workbench is a free and powerful alternative to Microsoft Project.” Sample projects, and a 308 page user manual also are available on this site.

CompTia
CompTIA Project+ certification is a global credential for project managers. Site has many interesting articles about PM and certification.

MIT Information Services and Technology Department
The site states that “MIT has become increasingly complex, control and management of the various project initiatives have necessitated the creation and implementation of a standard project management methodology.”

ProjectConnections.com
Typical of many PM communities. Some areas are open to all; others required membership.

Wikipedia
Overview and history of PM, with many valuable links and resources.