I haven't been totally unsuccessful with finding information on this topic. Some of the most helpful websites have been:
- This site has a good list of postmaster options to adjust in order to drastically increase performance on your DBMS. It also includes a list of hardware that can be upgraded or its capacity increased in order to further increase the scalability of your database. There is also a short section on query tuning.
- Another list of hardware configuration recommendations
- There are several blog articles/entries by Josh Berkus on PostgreSQL performance enhancing and query tuning. These very well worth looking into.