This website offers suggested methods for how to document community art collaborations as well as how to publicly share documentation (photos, videos, participant testimonials, etc) with a on-line format that will be accessible to a wide public.
The example is provided here based on documentation found in the archive of the Skol-CEDA co-creation projects ,  a three year community art collaboration that took place in Montréal, Québec from 2005-2008. This version of an on-line presentation (or public memory project) will hopefully spark some ideas for your group.
Affirming Collaboration: Community and Humanist Activist Art in Québec and Elsewhere 
Devora Neumark and Johanne Chagnon (Eds.) in collaboration with Louise Lachapelle, (2011), Montreal, QC and Calgary, AB: Engrenage Noir / LEVIER, LUX Éditeur and Detselig Enterprises Ltd. + DVD Documenting Collaboration – Download in pdf format! : http://celebrerlacollaboration.net/ 
“The goal of the Community Peace Mural was to bring all generations of our community together to create beauty and public art that represents a unified vision of peace. “
And another website with documentation from the project: http://siskiyouartscouncil.org/registry/mural.htm 
Community Arts Workbook: Another Vital Link – download as a pdf 
“This is a workbook for artists, communities and the public for anyone engaged in or who wants to become involved in community arts. It is designed to give some background on the application of community arts as well as provide hands-on tools advice, frameworks, techniques to help artists, cultural workers and communities plan, begin, complete and evaluate a community arts project.” – Starting on page 16, there are some suggestions for documenting methods as well as for public memory projects.
The Documenting Engagement Institute brought together nine Canadian artists, from a variety of disciplines, working in the field of community-engaged arts for three weeks at the end of January 2004. Each of the artists was financially supported to travel to Vancouver and participate in the Institute. A suite of short documentaries about current community arts practices was produced at the end of this period, with the intention to increase understanding and support of this field. These videos have been screened at festivals and are now available to order on VHS and DVD.