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We would like to eventually have the kata be synced with a Git based system. We intend to do this at some point but it is a huge effort, especially since we need to implement custom security.

In the nearer future we will make kata more open, so that anyone who has earned the ability can edit anyone else's kata. We already have a revision system in place (can be viewed from the menu within the kata editor).

I like the idea of having katas be wikis, but we'd really have to have editors and version control, and it's going to be a huge effort.

Yes. Even better, the kata directions should be wikis so we can all edit and improve them.

API that allows users to get basic information such as completed Katas with last completed and first completed dates. I could use this to build an app adding spatial repetition functionality.

I think it could be pretty easy to add the vm to the sandbox object passed in with the node runner.

Sandboxing code - Being able to run code in a new sandbox (and get the returned results) would be useful in crafting some test cases. Maybe extend the Test object to include Test.sandboxEquals(function, value).

I suggest reading the rest of these comments and updating the description further. Currently it's dificult to understand that you're looking to break a large array of 6+ people into the seperate floors they are on.

Average completion time, instead of top completion times would be useful to guage problems.

I can see why you did this. The question was a little misleading when it asked for "all" of the different ways you know how.

The community should be able to leave some kind of negative grade on a kata so that if enough of them accumulate it can be addressed.
It seems that there exists a few katas that have been abandoned by the authors.

Allow using lodash or underscore for JavaScript.

While JavaScript has some methods for manipulating collections in a functional way, like forEach/map/reduce/filter/some/every/etc. underscore provides a much wider collection of those.

Using such underscore methods like groupBy, indexBy, countBy, pluck, also ranges, chaining, and more would allow users, who enjoy the functional approach, to come up more interesting and concise solutions without having to reimplement basic underscore functionality.

Kata creators should be able to disable underscore in as simular manner other JS functions are disabled.

It would be useful to be able to request a correction or change from the original kata author. I've run across several now that have had incorrect directions. This usually requires me to read the details in order to determine what I might have missed.

This is absolutly correct. I had to change undefined to null in order to pass the tests. It should be corrected.