Beyond what comes with the PostgreSQL core, the contrib modules, and software available on pgFoundry, there are plenty of other programs which will make PostgreSQL easier and more powerful available from sources all over the Internet. There are actually so many available that choosing the right package for a requirement can itself be overwhelming.
Some of the best programs will be highlighted throughout the book, to help provide a shortlist of ones you should consider early on. This approach, where you get a basic system running and then add additional components as needed, is the standard way in which large open-source projects are built.
It can be difficult for some corporate cultures, ones where any software installation requires everything from approval to a QA cycle, to adapt to that style. To improve the odds your PostgreSQL installation will be successful in such environments, it's important to start early on introducing this concept early on. Additional programs to add components building on the intentionally slim database core will be needed later, and not all of what's needed will be obvious at the beginning.