Gettting back from the wishy-washy theorisation. This article is aimed at campaigning groups, but applies to any site which is motivated to engage its users:
With a clear set of objectives for your web site, and some new ways of structuring features, you can help guide your members to action on behalf of your organization; all while collecting the information you need without turning off supporters with scary data-collection forms
…not so sure I’m so happy with the emphasis on capturing personal data. Maybe it’s my European perspective.