My friend and I write a physics/art/geometry/math blog with gifs for illustrations: http://danielwalsh.tumblr.com/ - denser posts, but hopefully fun. (Here's also a list of posts, since they're so long that the blog can be hard to browse: http://danielwalsh.tumblr.com/tableofcontents )

I also recommend http://blog.matthen.com/ (tons of math gifs with source code) and http://visualizingmath.tumblr.com/ (lots of gifs and other images along these lines).

I liked the slinky one so much I submitted it.

Nice, thanks!

Your blog is now on my (short) reading list.

If you want books you can try these old books:

Dynamical Systems and Fractals (http://www.amazon.co.uk/Dynamical-Systems-Fractals-Computer-...)

Mathographics (http://www.amazon.co.uk/Mathographics-Robert-Dixon/dp/048626...)

Computers Pattern Chaos & Beauty (http://www.amazon.co.uk/Computers-Pattern-Beauty-Clifford-Pi...)

Fractals Images of Chaos (http://www.amazon.co.uk/Fractals-Images-Chaos-Penguin-Scienc...)

I suggest these because they all contain some kind of code.

All with source code:

http://asymptote.sourceforge.net/gallery/animations/

http://www.piprime.fr/developpeur/asymptote/animation-asy_as...

http://www.marris.org/asymptote/animations/index.html

Awesome

http://intothecontinuum.tumblr.com/ is my favorite

What isn't there a /r/ for on Reddit? Seems like they cover everything.

Inspired by that post[1] on Go a few days ago, I made a few animated parametric plots:

http://i.imgur.com/gUm1T5S.gif

http://i.imgur.com/xR5uqle.gif

http://i.imgur.com/SVvuRII.gif

[1]: http://www.pheelicks.com/2013/10/intro-to-images-in-go-part-...

Sometimes tumblr has interesting gifs: http://www.tumblr.com/tagged/math-gif

http://1ucasvb.tumblr.com/ mathey

http://dvdp.tumblr.com/ artsy

My personal favourite mathematical animation is the construction of Bezier curves: http://en.wikipedia.org/wiki/Bezier_curve#Constructing_B.C3....

This was exactly how I made sprite animations back in my Amiga demo coding days. Take a look at early C64/Amiga demos and you'll recognize these patters.