Use Postgres to check my passwords

I would like a pam module to check the user against a postgres
table and let them login if nessessary. Is there one?
This may sound stupid but currently we have a LDAP server running
the logins but since all the users need access to the database it seams
even more stupid not to store all the infomation in the same place.`
I find that LDAP is impossible to configure and a pam module that
just logged into postgres and read the encrypted database would be much
easier. It does however mean that postgres would be checking its security
against its self but I guess there is nothing wrong with that.
Might have to stop every table have access to PUBLIC though....

Peter Childs