Schema tool

A while back, I thought I remembered seeing a Mac OS X client for PostgreSQL which had a feature where it would display
agraphic schema of whatever database you connect to but I can't seem to find it again (web searching.)    I did come
acrossone post which said that this was a planned feature for pgAdmin.  I need to do a formal schema of a database
whichI have in development and it would be nice to have an automated tool, whether it connects to the database or uses
SQLtable definition code to generate graphics.  Is there such a thing?  if not, what do you all use?  OpenOffice Draw?
OmniGraffle?  

-Aram