Algorithm Wiki
algorithmist.com
algorithmist.com
This site was last modified in 2011, and represents a work in progress since it only covers a few algorithms such as convex hull and sorting.
https://en.wikipedia.org/wiki/List_of_algorithms
https://en.wikipedia.org/wiki/List_of_algorithm_general_topi...
I hope folks find them helpful.
In addition to visualizing the dynamic behavior of algorithms, I think we also lack good notation for their static structure; existing pseudocodes are verbose and pencil-unfriendly. APL was one attempt to solve that problem; I recently spent some time noodling around how to do a better job of solving it, specifically for the case of pencil-and-paper sketching, at http://canonical.org/~kragen/sw/dev3/paperalgo. That page doesn't work super well on phones due to depending on <abbr> to explain some things, and I think the notation's readability leaves something to be desired.
I was kind of hoping MediaWiki's addition of Lua would help with this kind of thing, at least for producing static visualizations, but I don't think it has. The closest thing I've found is maybe actually JsFiddle, but it lacks the linking and social interaction that make a Wiki work.
JsFiddle's security model of isolating the active part in a frame on a separate domain might be one way to keep such an active-algorithm-Wiki from suffering from worms and cookie thieves. Caja is another. We need to figure this kind of thing out in order to move to a decentralized web like IPFS, not just for centralized Wikis of algorithm visualizations.