Technical Assistance for Community Services (TACS) has served the nonprofit community in Oregon for over 25 years providing training, consultation, information, and resources that nonprofits need to do their work better.
Nonprofit Support Center: Based in California, their website includes resources, workshops and online publications.
Independent Sector: A national leadership forum working to encourage giving, volunteering, not-for-profit initiative and citizen action, with an extensive site. It offers many publications for purchase.
CompassPoint Research and Publications Page: extensive publications page from a consulting, research, and training organization providing nonprofits with management tools, strategies, and resources to lead change in their communities.