I've used lists where the the line between forum and mailing list is blurred. See:
http://www.cocoabuilder.com/
This is actually a web interface for a couple of mailing lists, and is a great tool for searching past posts. You can't post to the web site though - it is strictly a third-party web interface for the lists, but it's my first go-to for searching.
I realize you can search this list here:
http://archives.postgresql.org/pgsql-general/
but a more polished web interface of the list I think would satisfy everyone.
BTW, I performed a search on that page for the word "replication" and the result was very slow ("Searching in 863,821 pages took 25.1127 seconds").
Demitri