Addendum to yesterdays auditing SQL from black box third party applications
Well one area I did not think of yesterday and probably an area that is not of interest to the original poster on c.d.o.s is the possibility of commercial tools that can be used to grab all the SQL emitted from an application or from the other end arriving at the database (depends on where the tool is positioned). I should say that even though there are commercial tools they all do use techniques listed yesterday anyway, such as network packet sniffing.
The tools that come to mind first are Chakra from OR Solutions, Guardium SQL Guard and Entegra from Lumigent Technologies Inc. Links to all of these commercial tools are available on my tools page.