A few sorting algorithms - http://www.sorting-algorithms.com/
Visualization of Path-Finding Algorithms - http://qiao.github.io/PathFinding.js/visual/
Lastly, Mike Bostock (creator of D3) has a really cool bunch of algorithms over at his blog - http://bost.ocks.org/mike/
My sense is that animated visualizations are good at giving an intuitive sense about performance, but static visualizations are better for understanding how an algorithm works. If I was implementing a sorting algorithm I'd rather have one of Cortesi's visualizations on hand.
A friend posted this funny video series of sorting algorithms interpreted through eastern european folk dance today I just have to share! https://www.youtube.com/user/AlgoRythmics/videos
I also maintain a playlist with interactive explanations, which might be of your interest: https://gibbon.co/Steven/interactive-math-for-lasting-insigh...
I'm really interested in solutions for visually explaining what an algorithm does. Anyone have any other resources they like?