Here is a simple "editor" that I made over a weekend:
py.edit.js. It runs on top of
Google App Engine. It does simple things such
auto indent/auto dedent of Python code as you type it in,
evaluation of the code, and ability to
output as text or HTML. There is also a
"bookmarklet" mode -- which users can drag onto their menubar of their browser, and click on it to open up a "editor" mini-window on the current page that they are viewing.