We are heavy users of open source projects like Python, Twisted and more. Along the way we've built software we feel might be more generally useful, and are happy to have it available to the community at large.
Eliot is a logging framework for Python that allows you to understand the flow of actions within a running program, as opposed to the normal approach of logging a series of disconnected isolated data points.
Machinist makes it easy to create extremely powerful finite state machines in Python, almost a necessity when doing event-driven programming.