The pull to refresh animation is oft used to introduce a playful gem into an app. We currently have a boring spinner. This made me think, what am I expecting here. Well, notice how the app does not include our recognizable globe ?

My suggestion, pull down, and you will slowly reveal a Wikipedia globe that rotates from the backside to the frontside of the globe. Then when u release it, it will quickly spin (like it is wound up with a spring) and a puzzle piece will fly off it.