(Google Play Link)
This actually was uploaded a couple days ago, but I just got a video posted now.
Fireflies is a simple, serene backgroud featuring blades of grass blowing in the wind, and a collection of glowing fireflies swooping around amongst it. You can select from a few different forest backdrops, adjust the wind speed, and control the colors you get at different times of day.
This one's not laden with a ton of complex settings, but ultimately I really like the concept, and think it makes a very good background. Hopefully other folks agree!