From McKinsey, "Succeeding at open-source innovation: An interview with Mozilla's Mitchell Baker." This article offers three great tips for any size organization wanting to tap external ideas. Ms. Baker also talks about having a participatory culture.
Most of these social software technologies, at least the ones we set up, use tags (think tag clouds), folksonomies, taxonomies, , voting, reviews, recommendations, and search. This makes it quick and easy for experts as well as cross-collaboration teams to quickly and easily filter through ideas.