The official Cardboard app, developed by Google itself

Cardboard puts virtual reality on your smartphone. Try a variety of immersive demos on Android, and get inspired to build your own using the VR Toolkit at http://g.co/cardboard.

Earth: Fly where your fancy takes you on Google Earth.
Tour Guide: Visit Versailles with a local guide.
YouTube: Watch popular YouTube videos on a massive screen.
Exhibit: Examine cultural artifacts from every angle.
Photo Sphere: Look around the photo spheres you’ve captured.
Street Vue: Drive through Paris on a summer day.
Windy Day: Follow the story (and the hat) in this interactive animated short from Spotlight Stories.

To fully enjoy this app you’ll need a Cardboard viewer. You can make your own using the instructions at http://g.co/cardboard. Please check the list of supported Android devices in the FAQ at http://goo.gl/2MzqQa. You might experience issues if your device is not fully supported. Share your experience through our Google+ community http://g.co/cardboarddevs.

— Some features require pulling the Cardboard magnet, but you can just tap on the screen.