Over the last two years, Abu Musab al-Zarqawi established the Web as a powerful tool of the global jihad, mobilizing computer-savvy allies who inspired extremists in Iraq and beyond with lurid video clips of the bombings and beheadings his group carried out. After his death, the electronic network that he helped to build was abuzz with commentary about his death, with supporters posting eulogies, praising what they called his martyrdom and vowing to continue his fight.