In a Netezza database, what exactly does the 'LIST' privilege do? I understand what a 'SELECT' privilege does, but what does 'LIST' allow a user to do?
LIST is an object privilege, and is required to see the object (usually the object's name in a list).
SELECT object privilege does implicitly grant LIST, so you can always see a table that you can SELECT from, but LIST doesn't imply SELECT.
You can find information on Netezza object privileges here.