I think that the biggest feature that Pokemon Go will add, that will hopefully come soon, is the ability to broadcast your position.
This is something that I wish ingress had done. The game is a multiplayer game, there is no doubt about that. I'd love to be able to open map map, see that some of my friends are over playing at $foo location, and then go meet them there.
I built a chat app for pokemon go that allows people within a 5 mile radius to chat anonymously. It also has a crowd sourced pokemon spawn map where people can broadcast and located pokemons within their vicinity.
Once I can get Apple to stop rejecting it I'll post a link.
Ingress had at least a proxy for that - an in-game chat with distance-filtering, i.e. you could limit messages you see to sources closer than X kilometers. As for third-party tools, someone somehow made a player tracker once; I think it used changes in portal owners to narrow down your location.
This is something that I wish ingress had done. The game is a multiplayer game, there is no doubt about that. I'd love to be able to open map map, see that some of my friends are over playing at $foo location, and then go meet them there.