This, for sure.
I recently had to build some weather functionality and discovered Dark Sky right before they announced that they are discontinuing the API, and it's a real bummer because in my opinion nothing else comes close. There's a reason why Apple bought it.
Apple bought Dark Sky and closed the api for new devs. Supposedly they'll shut down the api next year for existing customers. If that happens, there are a bunch of sites/apps that would love to swap out their connection string to a similar service.