What I want to do is present the user with a sign-up form, which contains checkboxes for some of our mailing lists (discussion, not newsletter).
Is there a mailing list provide that has an API for this situation?
Alternatively, is there a provider that provides a widget (for inclusion on my site), which allows users to sign up in a similar way. The drawback of this approach is that data-collection will require a secondary form.
Any suggestions appreciated. Free solutions preferred, but all avenues investigated.