http://wp.tutsplus.com/tutorials/plugins/mini-guide-to-contact-form-7/

Contact Form 7 - Use Posted Form Data in Server Side Instead of Mailing

add_action("wpcf7_before_send_mail", "wpcf7_do_something_else");  
  
function wpcf7_do_something_else(&$wpcf7_data) {  
  
    // Here is the variable where the data are stored!  
    var_dump($wpcf7_data);  
  
    // If you want to skip mailing the data, you can do it...  
    $wpcf7_data->skip_mail = true;  
  
}