I must disagree with Jose’s point on “not ideal for leaders or those liking things done”. I believe discussion forums are as good (or bad) as group emails on that.
A good example of how effective a forum can be setting up actions is right here - the suggestion of creating a table to compare group e-mails and forums. It was done! A Wiki was created in response of that.
In my opinion, the response to a suggested action depends much more on how many “relevant people” are receiving the group e-mail or subscribed to the particular forum, than the kind of method used (e-mail or forum). People are usually very aware of professional peer review.