We had a live music themed event coming up where players would be presented with a stage set. There were eight different genres of music to be represented and we only had about a week to pull it off. It felt pretty empty without a room full of people to fill it up. So I opted to created silhouettes of people and put them on 3D cards. The cards were then animated up and down through this shader:
We could update the texture that scrolls across in world-space, the green areas controlled the y-position of the card and would make the silhouette appear to bob up and down. Red and blue would control x-position and z-position, respectively. By adjusting this texture and the speed value, it was easy to create a different vibe for each of the eight music genres.