A number of useful online and written guides are available online for those seeking more detail on the particulars of using BibTeX.  A few of the more helpful guides are noted below.

General BibTeX Guides

Getting to Grips with Latex - Bibliography Management by Andrew Roberts (concise, easy-to-use intro to BibTeX)

Managing Citations and Your Bibliography with BibTeX by Jugen Fenn (journal article about using BibTeX)

Tame the BeaST:  The B to X of BibTeX by Nicolas Markey (exhaustive guide to using BibTeX)

Using the natbib Package

Natbib Reference Sheet (consise summary of common natbib commands/options)

Natural Sciences Citations and References by Patrick W. Daly (comprehensive paper on using the natbib package)