The Joy of Slide Rules
Non-logarithmic slide rules (pdf)
The scale on a slide rule doesn't have to be logarithmic. It could be a triangular number scale.
Mystery of Log Log Scales
How to use Log Log scales to raise numbers to non-integral powers, like 3.142.71
Slide Rule Simulator
A windows EXE app that lets you construct and test a virtual slide rule. The help file is good - it explains how to actually do the various calculations on the rule. UPDATE: My own attempts at a slide rule emulator can be found here, here and here.
Graphical List of Scales
An image showing every possible scale you might encounter on a slide rule.
The SUV's of Slide Rules
The Pickett N4 probably holds the record for being the slide rule with the most scales (34), but the Faber Castell 2/84N "could be considered the culmination of the development of the slide rule by one of Europe's leading manufacturers." Better pics of the N4 here.