YouTube added support for 360-degree spherical videos and they're impressive. "You could let viewers see the stage and the crowd of your concert, the sky and the ground as you wingsuit glide, or you could even have a choose-your-own-adventure video where people see a different story depending on where they look," suggests YouTube.
For now, 360-degree YouTube videos are only available in Chrome and the YouTube app for Android. In Chrome you can use your mouse to drag the point of view, while in the Android app you can move your device around or manually change the point of view.
Here's a playlist with 360-degree videos:
If you want to upload your own panoramic videos, there's a help center article that offers more information. YouTube supports 5 cameras: Bublcam, Giroptic 360cam, IC Real Tech Allie, Kodak SP360, Ricoh Theta. For now, you need to run a script to insert metadata, but YouTube will try to make it easier to upload videos in the future.