1) Action Without Borders: http://www.idealist.org/, nonprofit resources.
2) Alliance for Nonprofit Management: http://www.allianceonline.org/,association of nonprofit managers and consultants to nonprofits from merger of Support Centers of America and Nonprofit Management Association.
3) The Giving Institute: http://www.givinginstitute.org/ promoting leadership in philanthropy.
4) American Philanthropy Reviews http://charitychannel.com/, career opportunities, discussion forums, etc.
5) ARNOVA: http://www.arnova.org/. Association for Research on Nonprofit Organizations and Voluntary Action - the major scholarly association in the field. Also moderated discussion group for researchers in the field (contact Roger Lohman at email@example.com and request that you be added to the ARNOVA_L list) American Society of Association Executives: http://www.asaenet.org/main/, professional association of association executives.
6) Association of Fundraising Professionals: http://www.nsfre.org/index.cfm, professional association of fundraisers
7) Charity Village http://www.charityvillage.com, Canadian site of nonprofit resources.
8) Council on Foundations: http://www.cof.org/, information about foundations.
9) Foundation Center: http://fdncenter.org/, search foundations.
10) International Center for Nonprofit Law: http://www.icnl.org/, resource on international nonprofit developments.
11) Internet Nonprofit Center: http://www.nonprofits.org/, a variety of resources and links.
12) National Center for Nonprofit Enterprise: http://www.nationalcne.org/, provides information and technical assistance on non-profit entrepreneurship.
13) National Council of Nonprofit Associations: http://www.ncna.org/,network of state and regional associations of nonprofit organizations.
14) New York City Nonprofits Project: http://www.nycnonprofits.org/, resource site for NYC nonprofits.
15) Nonprofit Times: http://www.nptimes.com/, news media outlet focusing on the nonprofit sector.
16) The Chronicle of Philanthropy: http://philanthropy.com/, major publication in the field