Postgres has a nice XML type. The advantage to doing this is at least you can rely on the database to guarantee well-formedness and use XPath functions to do th

Postgres has a nice XML type. The advantage to doing this is at least you can rely on the database to guarantee well-formedness and use XPath functions to do things like query the XML from SQL and build indexes on stuff buried within. Postgres 9.2 will have JSON support as well, but lacking accompanying functions it will be of limited utility.