Python is a very high-level programming language with a growing popularity in computational chemistry. It is one of the few languages that appeal to both software developers and scientists. Module extensibility is a design goal and people have written many 3rd party packages over the last 14 years. I started PyDaylight in 1998 as a way to simplify and accelerate chemical informatics development using the Daylight toolkit. In 1999 I co-founded the Biopython project to gather together bioinformatics components contributed by dozens of people. Others wrote and maintain packages for plotting, numerical algorithms, clustering, database access, GUI development and web programming. My talk will present features of PyDaylight then cover some of the details of the chemistry related packages and provide pointers to some other useful Python libraries.