One exciting new feature coming in PostgreSQL 9.3 is materialized views. Materialized views is really a mechanism for caching data of a query. It is especially useful if you have long running queries where the answers change infreqently. There are many things unfortunately that materialized views won't do where you are still better off with regular views.
They don't refresh themselves automatically. Thus requiring a cron job/pgagent job or a trigger on something to refresh.
They can't be user dependent or time dependent. For example if you have a view that does something like WHERE user=current_user(), then a materialized
view is out of the question.