http://www.rebol.com/docs.html
http://www.rebol.com/pre-view.html
if you prefer to use a browser as your front end rather than the cli/shell or make your own GUI in 'rebol/view' then you might try using the browser plugin.
check out the examples and the plugin here
http://www.rebol.com/web-plugin.html
http://www.rebol.net/plugin/demos/
i like Pongo the
Arkanoid style block game.
Author: Kurt
http://www.rebol.net/plugin/demos/pongo.html