Here's a recent interesting project which is completely unrelated to Pico-8.
http://superpowers-html5.com

It's an HTML5 game engine. More importantly, it's a free and open-source web-based development IDE. That is to say, instead of using Superpowers IDE to make Unity-like Superpowers games, you can add a plug-in to your Superpowers server to add additional project types, including (officially supported, in fact) LÖVE games and static webpages.

Superpowers is a real-time multi-user collaborative development environment unlike anything I've ever seen before, albeit still very much in its infancy. We should seriously consider adding Pico-8 cartridge support to it, as an alternative to using Pico-8's built-in IDE.

It would take a bit of effort, but with the result, you'd basically have the ability for any number of developers to simultaneously log onto a hosted Superpowers server, upload scripts and sprites, and download and run the resulting combined cartridge from the server in real time.

Superpowers is pretty much designed for small teams working together on game jam entries with strict time limits, getting all the work together immediately in real-time as individual files are changed and saved, without having to worry about committing and merging changesets like you would with Git or other collaboration methods.

... I don't know, just a passing thought. Probably wouldn't be worth it, considering how difficult it would be to manage Pico-8's arbitrary limits in a development environment meant to handle limitless modern PC games.