When developping a database tied application, you eventually come to a point where you get (at least) two tables with a parent/child relationship, such as for example a User table referenced by, say, a Post table (each post belonging to a specific user). That's basically the point where you need Zend_Db_Table relationships mechanism. the drawback of this mechanism is that, as far as I know, it does not produce joined queries to retrieve the parent data, but fires a query for each parent row. Thus instead of just using Zend_Db Relationships, I developped a simple yet effective auto-join mechanism that I called, in great simplicity, parent mapping. It supports multiple joins from multiple tables, remote fields specification and prefixing.
It is included in my db table class and you can see the interesting part of the code below for your convenience (Ignore the 3 first lines of the function as it is used for something else in my version of the framework).