For PBooks options, I will use a basic storage design of key value pairs. For example, for company name, there will not be a table column for company name, but instead a row in an options table with the column key of "company_name", and the column value containing "Example Company, Inc.".
In this way, developers (myself included) can create arbitrary key value pairs as needed. For the most part, the key value pairs will be simple data structures, but in the case of complex values, I'll need to decide whether to use serialized php, xml, or another more capable mechanism.