I was at MerleFest this weekend listening to Bela Fleck, Sam Bush, Jerry Douglas, Alison Kraus, etc.
When it got dark someone started selling these glowing juggling balls with an RGB LED inside that quickly strobed through all three colors, creating the illusion of constant white light. The effect of this was when you moved or tossed the ball around the white light’s persistence deteriorated, creating a cool rainbow ghosting trail. Maybe these are common in different circles but they are completely new to me.
Check the videos for a better idea of what I’m talking about. You can buy them from the same guy I bought them from at his company’s website: $14 for a set of three.