Cain and Abel
Biblical biography of the rivalrous siblings.
http://www.execulink.com/~wblank/cainabel.htm

Comparative Index to Islam: Cain and Abel
Discusses Islamic beliefs about the two brothers, including the folk tradition that they fought over women.
http://answering-islam.org/Index/C/cain_and_abel.html

Jewish Encyclopedia: Cain
Overview of the first murderer from the traditional Jewish perspective, including apocrypha and Talmudic commentary.
http://www.jewishencyclopedia.com/view.jsp?artid=27&letter=C

The Secret of Happiness and Other Insights from Cain and Abel
Analysis of the first murder based on the Jewish Talmud.
http://www.aish.com/literacy/exploring/Cain_and_Abel_Happiness_and_Other_Insights.asp

Cain
Profile of the wicked son of Adam from a joint Lutheran and Catholic bible study project.
http://www.aboutbibleprophecy.com/p144.htm

Jewish Virtual Library: Cain
Brief profile of the Biblical killer, with links to pertinent Torah passages.
http://www.jewishvirtuallibrary.org/jsource/biography/cain.html

Can and Abel - Wikipedia
Overview of the first murder with outline of the story, depictions over history and references.
http://en.wikipedia.org/wiki/Cain_and_Abel

The Mark of Cain
Evangelical Christian commentary on Cain's guilt and God's mercy.
http://www.pbc.org/files/messages/3394/0322.html