Jewish Encyclopedia: Jethro
Overview of the father-in-law of Moses from the traditional Jewish perspective, including rabbinic commentary.
http://www.jewishencyclopedia.com/view.jsp?artid=258&letter=J

Yisro
Parsha on the interplay between Jethro, his son Chovav, and his son-in-law Moses.
http://www.mesora.org/yisro.html

Hobab the Kenite
A Christian examination of the life of Moses' father-in-law.
http://www.heraldmag.org/literature/bio_2.htm

How Raguel Suggested To Moses To Set His People In Order
Chapter about the advice of Jethro to his son-in-law by the first-century Jewish historian Josephus.
http://www.interhack.net/projects/library/antiquities-jews/b3c4.html