Great tutorial Dave, but from an SEO perspective you would be alot better off using HYPHENS instead of UNDERSCORES.
Underscores are used by coders to made code readable, but Google, MSN, and Yahoo see them as continuations, however hyphens are seen as full word breaks (spaces) -- which is much more valuable for SEO
pizza_dough -- will only get a direct hit on "pizza_dough"
pizza-dough -- wil get hits for both PIZZA and DOUGH
I've bookmarked this thread bro ... great job!