While exploring some sites (actually, I was just following my mouse and letting it click on things that seemed interesting) I saw a slide rule giving some scientific credibility to an entrepreneur's site:

http://www.kleinbottle.com/

I'm not sure what rule it is, but I enjoy the site. If I wasn't in the midst of a personal economic recession, I would buy the Klein hat and Mobius scarf.

John Schudy
Missouri, USA