Florida State University
Florida State University: Lightning, a Natural Capacitor
Text and animated graphic show how lightning is an example of a natural capacitor.
Other
Fun Science Ring: Leyden Jar
Everything you need to know about how Leyden jars work, and how to construct your own. Many pictures, references, other sites, other electrostatics projects and topics.
Other
Farad Net: Electrolytic Capacitor Book
An entire book on electrolytic capacitors. Originally published 1938 and website version is an in-progress update. Part 1 is sufficiently general and current to give one a background in capacitors and electrolytic capacitors.