A good socializing app for the NYC area?

Dating and sex are covered by a multitude of apps but I'm won. I know there are groups for meet-ups, et cetera, but is there an app for smaller scale, spur-of-the-moment activities? "Want to catch a specific movie at Sunshine Cinema tonight, 2-3 people interested?" "Dog walking buddy wanted." I'd like to widen & diversify my social circle a bit. Maybe hang out with ppl and go to events that my Mario Karting & beer at the bar downstairs roommates of 4 years aren't always up for. Any experiences with them? Happy for any recommendations! :)