The Noun Project - Swing Icon actually swings on mouse over.
/via Shitty Posters
It is a shame there isn’t more consistency in the icons. It seems like they have 4 or 5 different styles, and none of them really mesh with each other.
It would be great if there was a base language or rule set for all the icons to make them really feel like one cohesive unit.
It also makes me sad that only the swing one was animated. There are so many that end themselves to a little motion, and I think looking in to the combination of graphical representation and motion could be something that would benefit the web space.