Monitoring & analysing your PostgreSQL server logs with PgFouine provides you with a way to see which queries are performing badly and need optimisation. It can also provide insight into busy periods and give some basic query stats such as the number of INSERT, DELETE, UPDATE, and SELECT operations.
Well I have had my head buried in Postgres tuning parameters today. There are so many different options to look at and no real definitive guidelines out there, and to make matters worse you can really impede performance with incorrect tuning parameters which is probably counter productive if your interested in tuning for performance :-).
I have read a lot of blog posts and articles today and will list the ones I found most helpful below.