My favorite tool for this kind of analysis was pgAdmin3, which had a very nice diagramming output for EXPLAIN ANALYZE which you can see here [0]. Hovering over the various images in the diagram would display their time, rows, and which statement caused them.
There is also this excellent post which shows how to break down an EXPLAIN and reason about the performance [1].
[0] http://www.postgresonline.com/images/journal/explain_plan_5....
[1] http://www.postgresonline.com/journal/archives/27-Reading-Pg...
Is there a tool for Postgres that will provide optimization tips over time, based on actual queries run against the DB?
Seems a much more efficient approach than analyzing and diagramming (sometimes) complex explain results.
Probably the closest thing to what you are asking for is pgBadger [0]. If there is a better tool I'd love to hear about it.