This sort of thing has been under consideration for a while now, actually. Whether or not it gets linked with the NWN incarnation or not is uncertain, but out-of-game mini-games and/or tools that tie back into some kind of in-game benefit/utility are things we definitely want to do. It may not be a mobile app but rather something web-based...at least in its initial incarnation.
We actually have several ideas on this front, and at least one might see the light of day before some other efforts are fully realized.
Neverwinter MMO does this sort of thing. using dice rolls for outcome and turn based play dungeon crawl uses a seperate web site.