From their website: "IAP2 is an association of members who seek to promote and improve the practice of public participation in relation to individuals, governments, institutions, and other entities that effect the public interest in nations throughout the world"
They run a conference, have a newsletter, and published a great 'toolbox' document on many different practices - http://www.iap2.org/boardlink/toolbox.pdf - this was a significant source for the Citizens Science Toolbox.