I have the user's ip saved in the variable $ip. However, I can't seem to get it to save in the database. I think I just don't understand your query method exactly, even though it seems to make perfect sense to me.

$query = sprintf("INSERT INTO users
                    SET
                        username = '%s',
                        email = '%s',
                        password = '%s',
                        firstname = '%s',
                        lastname = '%s',
                        address = '%s',
                        city = '%s',
                        state = '%s',
                        zipcode = %s,
                        junk_key = '%s',
                        date_created = NOW()",
                    db_lower($params['username']),
                    db_lower($params['email']),
                    db_lower($real_key),
                    db_lower($params['firstname']),
                    db_lower($params['lastname']),
                    db_lower($params['address']),
                    db_lower($params['city']),
                    db_lower($params['state']),
                    db_lower($params['zipcode']),
                    db_lower($junk_key)
                    );