Frax is a beautiful, feature-filled app made by the people who were making fractal lab. You can watch their homepage tutorial video for the app in action and then look at their high quality render samples and user created gallery.
Similarly, here are some fractal flythroughs. I hope a versatile 3D fractal explorer is released some day, with virtual reality support.
The sound of sorting is a program that visualizes and audiolizes various sorting algorithms. It is a ton of fun, from hearing crazy pacman noises to trying to figure out how the different sorting mechanisms work to seeing which algorithms are best for different data sets.
Bonus Hungarian quicksort folk dance.
Thanks to another Vi Hart video, this time I’ve learned all about flexagons. They are very fun to make; kind of like a cross between a Möbius strip and an origami fortune teller.