Hey SP, I've been losing weight over the last year by myself, and for the last leg of my journey I have found community to be a great motivator for me. This is what mainly drew me to SP in the first place.
There are many time where I would like to check up on threads, Spark Mail, Spark Teams, and Spark Pages but I am away from my computer and am on my iPhone (now is one such time). I realize that I can access these things via the normal website on my phone, but it would be even greater if there were a SP Social App (much like the one for trackers, recipes, and produce). Just a suggestion (that I would love to see come to fruition).