With some add-ons/changes/new options the blog could be used as an easy market- and eventplace. If possible i'll use the marketplace on my website sponsormeter.nl to get more visitors and members. Or to build a seperate marketplace. This option can also raise the sell of Website X5 prof.

To use the blog as an easy market- and eventplace 

-the visitor can choose the (new) options: (normal) message/to buy/to sell (for supply and demand)/event, new or used, category/subject, adress, expirantion date etc.
-the visitor must be able to upload at least one picture to add to his message/request/offer
-the owner of the message can change or delete his message, text, options and picture(s)

If not possible, maybe you can develop a new simple market- en eventplace and offer it as a new project?