Derek's Virtual Slide Rule Gallery
Derek Ross has some magnificent virtual slide rule available for use. They are very useful if you don't own a slide rule and they're also great to use on screen.

Greg Schechter's Slide Rule Widget
An interesting creature this! You an now have a slide rule widget!

Hemmi 45 Virtual Rule
Another virtual slide rule, this time a Hemmi 45 compliments of Atom.

Stefan's Historical Computing Devices
Stefan Vorkoetter's virtual Aristo 970 Mulitlog.

Steven Burton's Home Page
This is about the only desktop software that appears to be available that actually installs slide rule software. High configurable and easy to use.