I’ve always loved weird, Googley bits like this: Type “I’m feeling curious” into Google search to get a random, fun fact. (Go ahead, try it; I’ll wait.) And now on iPhone 6s, when you hard-press the Google app icon, you’ll get an “I’m Feeling Curious” menu, shown below.
Incidentally, my single favorite 3D Touch gesture is voice search in Google Chrome. For some reason I’ve never used it from within the app, but now that I can hard-press the Chrome app icon, I use it all. the. time.