TOMBSTONE, Ariz. — They came by the hundreds Friday, men and women from across the nation, hearts brimming with righteous anger, determined to staunch the flow of illegal immigration. Some wore pistols slung low on their hips. Others walked the dusty streets in leather cowboy hats, wearing buttons that read: "Undocumented Border Patrol Agent." There were pilots, window washers, private investigators and exterminators.