I would like to group friends, and be able to use the groups for advanced privacy settings. For instance, I would like:

* Privacy Option for inventory: Shared with group(s): <checklist>
* Privacy Option for decklists: Shared with group(s): <checklist>

I would like to keep my inventory private, but shared with my teammates. The option to set a password for the inventory and each individual decklist (the «Password protected» option) is clumsy and time consuming. Just to group friends in a private group would be better.

In time more advanced features could be built, for instance it would be able to add cards in friends' inventory they don't play (not content of "deck built" tagged decklists) to the view of decklists.