There is a need for an up to date listing of OFX compliant plugins / known to work on Natron (same difference). People would benefit from going to a page and seeing people's ratings of these.
Plugin vendors need to be encouraged to support their products on Natron and I think a Plugins Directory would help cause that to happen, because vendors can put their own listing on and say what they want about their product, and users will rate and comment. So sales will result.
To keep each developer's advertising modest, the page can be so constructed that each plugin gets only a fixed amount of page space. Also, by having the actual OFX bundle binaries on the server, these spaces can be automatically generated similar to the new plugin reference documentation system.
Or it could be a simple wiki. There is already a wikipedia entry but it doesn't show enough on one page, and especially lacks the user ratings.
The Foundry used to have a kind of plugins gallery / market with an integrated installer - have they discontinued that?