As you know, the quality of what you can find on the internet varies enormously.  Thus, I've compiled a list of things that I'll vouch for as worthy of your time.  This doesn't mean that I think you should agree with everything you'll find here, of course!

General ethics sites

• Ethics Updates
• Brown Electronic Article Review Service (BEARS) in Moral and Political Philosophy
• EthicsWeb Bookstore
• Stephen Darwall's Home Page
• The American Journal of Bioethics
• Left2Right (a blot of philosophers and others on matters moral and political)
  

• Ethical theory
• "Consequentialism," from the Stanford Encyclopedia of Philosophy
• "Virtue Ethics," from the Stanford Encyclopedia of Philosophy
• " The Natural Law Tradition," from the Stanford Encyclopedia of Philosophy
• "Reflective Equilibrium," from the Stanford Encyclopedia of Philosophy
• "Theological Voluntarism," from the Stanford Encyclopedia of Philosophy

• The meaning of life and death
• "Death," from the Stanford Encyclopedia of Philosophy
• "Death," by Thomas Nagel

• Killing and letting die
• "Doing and Allowing Harm," from the Stanford Encyclopedia of Philosophy

• War, violence, and self-defense
• "War," from the Stanford Encyclopedia of Philosophy
• "Just War Theory," from The Internet Encyclopedia of Philosophy
• JustWarTheory.com, a large collection of resources
  

• Famine relief
• "Famine, Affluence, and Morality," by Peter Singer
• "The Singer Solution to World Poverty," by Peter Singer
  

• The animals issue
• Peter Singer's "All Animals Are Equal"
• "The Case for Animal Rights," by Tom Regan
• "Why Animals Have No Rights" (or "The Case for the Use of Animals in Biomedical Research"), by Carl Cohen
• "A Modest Proposal," by Richard Hanley
  
• "The Moral Status of Animals," from the Stanford Encyclopedia of Philosophy
• "Animal Consciousness," from the Stanford Encyclopedia of Philosophy
• PETA:  People for the Ethical Treatment of Animals
• FactoryFarming.com
• Roadkill 2005
• The Vegetarian Site

• The environment
• "Environmental Ethics," from the Stanford Encyclopedia of Philosophy

• Abortion and infanticide
  
• "Abortion," by Judith Thomson (1995).  Replies to Thomson (scroll down a bit to see them. . .)
• "Abortion, Bioethics, and Personhood: A Philosophical Reflection," by Francis J. Beckwith

• Cloning and Stem-Cell Research
• "A Wolf in Sheep's Cloning?" by Richard Hanley
  

• Suicide, euthanasia and physician-assisted suicide
• "Assisted Suicide: The Philosophers' Brief," by John Rawls, Judith Jarvis Thomson, Robert Nozick, Ronald Dworkin, T. M. Scanlon, and Thomas Nagel
• "A Right to Choose Death?  A moral argument for the permissibility of euthanasia and physician-assisted suicide," by F. M. Kamm
• "Against the Right to Die," by J. David Velleman (See also here)
  
• "Against the Sanctity of Life," by Peter Suber
• "Voluntary Euthanasia," from the Stanford Encyclopedia of Philosophy
• "Suicide," from the Stanford Encyclopedia of Philosophy

• Capital Punishment
• "Punishment," from the Stanford Encyclopedia of Philosophy
• "Legal Punishment," from the Stanford Encyclopedia of Philosophy

• Sexuality
• Alan Soble's online essays
  
• "Homosexuality," from the Stanford Encyclopedia of Philosophy

• Affirmative Action and Race Relations
  
• "Affirmative Action," from the Stanford Encyclopedia of Philosophy

• Distributive Justice
  
• "Distributive Justice," from the Stanford Encyclopedia of Philosophy
• "Redistribution," from the Stanford Encyclopedia of Philosophy

• Materials on Peter Singer, Ira w. DeCamp Professor of Bioethics at the University Center for Human Values at Princeton University
• Singer's c.v. (pdf)
• Peter Singer site
  
• "Professor Death," an interview with Singer at salon.com
• The President of Princeton defends Singer's controversial appointment
• A debate between Peter Singer and Richard Posner about animal rights
• "Why Are We Afraid of Peter Singer?" by Jeff Sharlet
• "Dr. Jekyll and Mr. Hyde," by Jenny Teichman
• "You're an Animal," by Norah Vincent

• Applied Ethics Links Page
• Jensen's General Links Page
• Jensen's Philosophy and Science Fiction Links Page
• Jensen's Ancient and Medieval Philosophy Links Page
• Jensen's Modern and Contemporary Philosophy Links Page