How can I put the results of a MySQLi prepared statement into an associative array?

Try the following:

$meta = $statement->result_metadata(); 

while ($field = $meta->fetch_field()) { 
    $params[] = &$row[$field->name]; 
} 

call_user_func_array(array($statement, 'bind_result'), $params);            
while ($statement->fetch()) { 
    foreach($row as $key => $val) { 
        $c[$key] = $val; 
    } 
    $hits[] = $c; 
} 
$statement->close(); 

First you get the query metadata and from that obtain all the fields you've fetched (you could do this manually, but this code works for all queries rather than building by hand). The call_user_func_array() function calls the mysqli_stmt::bind_result() function for you on each of those parameters.

After that it is just a matter of running through each row and creating an associative array for each row and adding that to an array resulting in all the results.

Update: Since PHP 5.3.0 you can get a mysqli_result object that provides a fetch_array method.

$sql = 'SELECT photographers.photographer_id, photographers.photographer_name
    FROM photographers';

$stmt = $conn->prepare($sql);
$stmt->execute();
$result = $stmt->get_result();
$data = $result->fetch_array();