The following applies to at least postgresql 8.1 "debian way" installs.

I have a large database and do not want any type of automatic analyze or vacuum. Each time pg is reinstalled, I find VACUUM ANALYZE's start running for days without my directive. I also find that I have forgotten how to get rid of these automatic vacuums. Of course I always set autovacuum to false in the postgresql.conf file and the autovacuum.conf file - but still the multiple unwanted VACUUM ANALYZEs appear in Server Status.

There are many references to autovacuum and pg_autovacuum in settings and pg_catalog. However there is yet another way that automated unasked-for vacuums get started. This is by something which doesn't use autovacuum in the name so a "locate autovac" doesn't find it. The #postgresql channel (  irc.freenode.net ) may also not be able to tell you either because most of the participants do not install pg "the debian way."

Look in /etc/cron.d/

Here you may find postgresql-common and within it, a line to run /usr/sbin/pg_maintenance. Ah... pg_maintenance. There's the file I used to find and rename just to prevent it ever, ever getting started by anyone or any process for any reason. I know it's right for some databases but not mine.

If you disable the cron for pg_maintenance - be sure you are taking care of the maintenance in your own routines. You can experience catastrophic data loss from transaction id wrap around after 4 billion transactions otherwise. Please be sure to read: Preventing Transaction ID Wraparound Failures from the postgresql.org website.