BrainFreeze is an SQLAlchemy plugin that supports object composition (as opposed to class inheritance). Google for "composition vs inheritance" to get the general idea. Another way to think of BrainFreeze is that it's a plugin for proxying properties on one-to-one related objects. BrainFreeze uses SQLAlchemy's AssociationProxy for the python properties, only BrainFreeze goes the extra step of making those properties query-able using SQLAlchemy's session.query() machinery.
Checkpoint is a simple media archive management system.