An emacs-like text editor.
Chremacs is a surprisingly complete version of emacs, a powerful text editor with a long, rich history.
This is a simple Google App and does not do everything one would like, yet. For example, it does NOT save work as you go, nor does it trap window closes -- if you close the window, your unsaved work is gone. But it allows you to open, edit, and save text files to local storage and Google Drive.
For any experienced emacs user, it provides an incredibly high level of productivity.