October 2001: The conviction of “Portland 7” case was substantially helped after a local police officer encountered the suspects engaged in target practice. The police officer had been sent to the area after a local citizen notified police that he heard gunfire.
September 2002: Members of the “Lackawanna 6” are arrested. FBI first becomes aware of their activities in June 2001 when a local Muslim community member tips off the FBI.
March 2002: FBI become aware of a possible terror plot by Imran Mandhai (and later Shueyb Jokhan) after they are notified by an American Muslim named “Saif Allah” who attended Mandhai and Jokhan’s same mosque provides a tip.
June 2003: FBI receive two tips from community members notifying them “military-style training” was being conducted suspect by Ali Al-Tamimi. The tip set in motion an investigation later leading to the arrest of the so-called “Paintball 11” in Northern Virginia.
August 2004: James Elshafay and Shahwar Matin Siraj are arrested largely based on the controversial use of an informant in the investigation. However, NYPD were first notified of Siraj after a Muslim community member anonymously notifies New York police about consistently troubling rhetoric coming from the suspect.
February 2006: Muslim community members in Ohio provide information helping to arrest and eventually convict 3 suspects planning attacks in Iraq.
July 2009: Mosque leaders in Raleigh, North Carolina, contact law enforcement to notify them of “violent, threatening action … considered to be dangerous” leading to the arrest of Daniel Boyd and 6 other individuals.
November 2009: Five Virginia Muslim youth are arrested in Pakistan, allegedly seeking to join a terror group, after family members told American federal authorities they went missing.
April 2010: Senegalese Muslim Alioune Niass first spots the suspicious vehicle used as a bomb to attack Times Square in New York City. Clues from the vehicle and defused explosive immediately led to the suspect, Faisal Shahzad’s, arrest.
June 2010: Suspects Mohammed Mahmoud Alessa and Carlos Eduardo Almonte are arrested, after the FBI first receives an anonymous report in 2006 from one of the suspects’ family members. News reports indicate one of Alessa’s family members provided the tip.
Of course, there's more at the American Prospect.
