I think Scott's lawn care site does an outstanding job providing very helpful information in a discussion format. The branding matches the root web site dead on, it looks very professional yet fresh and appealing, and real live experts (e.g. "Scotts WebLawn Guy") monitor the site providing resolution to otherwise elusive problems. Accounts are integrated with the scotts.com site but one doesn't need to log in to view discussion postings. The technology is Fuse Talk available in Cold Fusion and ASP.Net. Basic edition is $129.
Finally, this vehicle creates a huge marketing win for Scott's. For example, check out this softball thread. Scotts WebLawn Guy knocks one out of the park when asking "If Scotts could make (product idea) that would (blank), I would definitely buy it." and receiving 21 posts!