The most prominent campaigning anti-spam organizations have been the CAUCE family, which started in the U.S. and has spread to Canada, India and other parts of the Asia-Pacific region.
Unspam Technologies is a relatively new organization focussed on legal responses to spam - from do-not-call lists to their Project Honeypot, which aims to unmask spammers harvesting email addresses so that they may be prosecuted.
Many other anti-spam organizations conduct business in a niche part of anti-spam: spam filtering companies, news sources or blogs, scams or reporting.
One notable example is called "InBoxRevenge.com". This is a meeting place of volunteer anti-spammers who pool knowledge ad resources. It is not uncommon for such sites to come under Denial of Service attacks from the criminals whose livelihoods and misdeeds become a focus attention.
One such attack was launched on InBoxRevenge.com in late October/early November 2009. IP addresses of the attack bots are recorded in this wiki under IBR Attack