The last posts from @brian_pond, @olamide_shodunke, and @peterg would create a “marketplace” which is strongly against in the ERPNext development path.
As my post here ERPNext 14... What would you like to see? - #34 by rahy the incorporation of apps should be decided, otherwise it will be confusing. And contribution to the core will be low.
Anyway, I see that this discussion has deviate from the original topic.