Death Penalty Information Center: 
Excellent US based site, packed with detailed information about a wide range of topics related to the Death Penalty in the US.

Amnesty International USA
: This site contains lots of useful information about the death penalty in the US and worldwide.

Murder Victims' Families for Reconciliation
: A US based web site of an organization which focuses on the role of victims' families in Capital cases.

Murder Victims’ Families for Human Rights: 
A non-governmental organization of family members of murder victims and family members of the executed.

Death Penalty - ACLU of Northern California

Death Penalty Focus: Death Penalty Focus of California is an active, non-profit organization dedicated to the abolition of capital punishment through grassroots organizing, and research.

World Coalition Against the Death Penalty: The World Coalition Against the Death Penalty brings together abolitionist organizations committed to working together in line with common statutes. It is registered in France.‎