At present we have the Forge for open source modules etc., on the Dnn website but this is buried and hard to find if you don't know what the Forge is for new comers to the community.
On the Dnn Store you can offer your free modules and skins. The problem with the Dnn Store is that if a person doesn't know there are free modules, they won't be downloaded as much, again the OS modules and skins etc., get lost in the masses.
My suggestion is to create a 'Free zone' or 'Free category' on the Dnn Store for people to place their free modules etc., into ( and only if there are truly free, in other words no free trails etc.).
This way it would stimulate people to use the Dnn CMS knowing that creating a site can be done on a low budget etc.