I have a Tumblr account as well as this blog, it's a fun mathematical space, and the reblogging is an interesting spin on curation. Here's a post I wrote for a 'my favorites' at Twitter Math Camp 16 to help #MTBoS folk get started on Tumblr.
One of my favorite ever mathart sources was @tilman's http://geometrydaily.tumblr.com/. There's a site that has a bit of a similar flavor, http://www.dailyminimal.com/.
The other day, they had this:
Nice, right? Rotating ellipses... what I always try to think of is how can this be generalized? Rotating conic sections (definitely sometime will do!)... what if it didn't just rotate around a point? What if it followed a curve? One idea I really liked from the dailyminimal was having a start and stop point. So ...
On GeoGebraTube, so go play. If you make something cool, let me know!