Postgres.app is the easiest way to get started with PostgreSQL on the Mac. Open the app, and you have a PostgreSQL server ready and awaiting new connections. Close the app, and the server shuts down.
Whether you're a command line aficionado, prefer GUIs, or just want to start making things with your framework of choice, connecting to Postgres.app is easy.
- PostgreSQL Website - The source for all of the latest PostgreSQL news and information.
- PostgreSQL Docs - The canonical reference for everything you need to know about PostgreSQL.
- Postgres Guide - A promising new PostgreSQL resource that reads well and introduces advanced topics in a way that's easy to understand.