I’ve just released version 2.0 of my WordPress/bbPress plugin, bbPress Digest. This version incorporates two new features: weekly digest and one-click forum subscription.
Weekly digest means that administrators can enable users to choose should they receive digests once daily or once weekly.
One-click subscription means that administrators can enable users to include forums in digest directly from forums page, without need to go to the their profile page.
Both of this features are suggested by users so if you have one too, send them to me and they might be included in future versions.