Yishmael and Hagar: A Perspective
Rabbinic commentary on some of the questions raised by Abraham's apparent abandonment of his son.
http://www.torah.org/learning/rabbis-notebook/5760/vayera.html

Jewish Encyclopedia: Ishmael
Overview of Abraham's first-born son from the traditional Jewish perspective, including Talmudic commentary and apocrypha.
http://www.jewishencyclopedia.com/view.jsp?artid=277&letter=I

Catholic Encyclopedia: Ismael
Commentary on the spurned son of Abraham from the traditional Catholic perspective.
http://www.newadvent.org/cathen/08192a.htm

Ishmael
Biblical biography of the wicked son of Abraham from a general Christian perspective.
http://www.execulink.com/~wblank/ishmael.htm

Abraham and the Child of Sacrifice: Isaac or Ishmael?
Deconstruction of the extra-Koranic Muslim tradition that Ishmael, not his brother, was the intended sacrifice of Genesis.
http://answering-islam.org/Shamoun/sacrifice.htm

Prophets and Spirits of Islam: Ishmael
Profile of the father of the Arabs from a Muslim perspective.
http://web.uvic.ca/~rpn/files/ishmael.html

Prophet Ishmael
The traditional Muslim view of the ancestor of Mohammed, with Koranic references.
http://www.angelfire.com/on/ummiby1/ishmael.html

Ishmael
Profile of the son of Abraham from a joint Lutheran and Catholic bible study project.
http://www.aboutbibleprophecy.com/p141.htm

Concerning Ismael The Son Of Abraham
Chapter on Abraham's illegitimate son by the first-century Jewish historian Josephus.
http://www.interhack.net/projects/library/antiquities-jews/b1c12.html

Jewish Virtual Library: Ishmael
Brief profile of the illegitimate son of Abraham, with links to pertinent Torah passages.
http://www.jewishvirtuallibrary.org/jsource/biography/ishmael.html