I've been developing Pork.dbObject on my own. (A simple PHP ORM and Active Record implementation)
The main reason is that I find most ORMs too heavy.
The main thought of Pork.dbObejct is to be light-weight and simple to set up. No bunch of XML files, just one function call in the constructor to bind it, and an addRelation or addCustomRelation to define a relation to another dbObject.
Give it a look: Pork.dbObject
