Geoffrey Grosenbach has been designing and developing web applications since 1997. You might recognize his soothing voice from the Peepcode screencasts, of which he is the founder. Or maybe you also know he is nuts about road cycling, a hobby and so much more!
Shows the Seeing Is Believing library (runs a ruby file, and spits the source code back out with comments next to each line, showing what it evaluated to). Also shows how to customize it, and how to use the provided snippets.
With legitimate testimonials by Corey Haines and Aaron Kalin!