I'm actually interested in this thread. I feel like there are a number of good apps I'm missing out on.
The ones I use regularly are:
Eat 24 - food delivery
Grubhub - food delivery
City Eats - restaurant reservations
OpenTable - restaurant reservations
Parkmobile - parking meter payment
Uber
Xfinity to go - can control my home DVR
CityMaps2Go - awesome app for international travel. locational maps that use your cell signal and not data to pinpoint your location (i.e., it's free)
Sky Guide - shows all of the constellations in real time based on which direction you point your point. nerdy fun.
I also have a number of others as well that are pretty common (ESPN, Soundhound, Pandora, Netflix, etc.)