The Living Thing / Notebooks :

Atom

a text editor I seem to be using

Atom — a text editor made by Github, very extensible because much like emacs, it’s mostly written in a dynamic language (javascript) and is open source. Unlike emacs, it’s not an evolutionary cul-de-sac. Probably the hottest hotness at the moment. Powerful. Slow and RAM-hungry. I use it a lot despite this, because it is vibrant.

Notable extensions:

Atom as a platform

People can and do build whole IDEs in atom.