"This free, dW-exclusive tutorial introduces you to a powerful
Internet-enabled scripting language called Rebol. This tutorial
provides clear demonstrations of Rebol fundamentals, including
detailed explanations of the parts of Rebol that differ from more
conventional programming languages. It's designed to make learning
Rebol really easy."
"After a quick (2 minutes, tops) registration, you can go
through the 45-minute tutorial on the Web, download a PDF, or
download a zip file."