Relational databases are great at storing tables. ZODB is great at storing trees, even graphs. Let us focus on trees today. Have you ever tried choosing a county in Skype? You have to choose from a list of 130 countries. It is unnatural. Much easier to use a tree to find a country. Europe->Central Europe-> Poland. I think that more web applications should use trees. And in the python world, the natural place to store a tree is using the Persistent classes provided by the ZODB.
Here is a way to traverse relational databases from Pyramid.
I invite you to Register and then link to your own blog postings and