Fantastic to see this thread and its contents. The proposal so far seems very logical, fair and balanced.
I would prefer some type of rating system, however I easily concede that unless thought through it could be possibly twisted. However Ratings help one to get an insight into whether the product is well supported, decent value, etc... and can be used as a very constructive tool for customers. That said, I do agree that comments can get messy and ugly.
I think the directory would be best categorized by functionality. Each author can submit where applicable. A log would be good, product name, description and a link, however if the person viewing is not a licensed vB user, redirect them to a permission denied page.
I also think that having the author be able to update the version number a last updated information could be useful (could be really useful to keep a browsable history of this information). Not a big deal - just thinking aloud
I hope that custom programmers and style makers will also contribute to the directory, thereby making it an easy resource for customers to find the people they are after.