Ok the application store by nokia at:
http://store.ovi.com
Why not have a paid application store for Maemo, you have a great community and with a paid store perhaps you will get developers such as Sygic etc who have a primary interest in making money rather than contributing free apps.
In other words perhaps you will attract more developers wanting to tap into this great and loyal community.
The Maemo extras repo is on every N900 by default !