Jeffrey McManus (pic) gave me a pre-tour of Approver.com a few weeks ago. Interesting product, it basically provides a workflow so those who you select can approve content (a variety of options) before it comes back to you.
I see this as a feature or component for a variety of other applications. Also, it would be great for writers that collaborate, folks that want approval of those party pictures before going live and could be a checkpoint for a hybrid Web 2.0 companies that need to share data. See VentureBeats review to learn more.
Check out the Approver blog to learn more.