Most of the participatory tools are circle based, e.g circle, world cafe (& variations of it), open space technology and collective story harvesting. The most common ones are introduced here, but there is also appreciative inquiry, dynamic facilitation, wise action and theory u- coaching process to mention some more.
The tools always depend on the process: what is the issue being explored, who are the stakeholders, what kind of harvesting is needed? Is there a need to create a self-organizing social infrastructure along the process? More about that under Building Community.