>> Using \d+ exposes a column "Description". Now, how do I add a
>> Description to a table and/or a column? There does not seem to be any
>> option during CREATE DATABASE or CREATE TABLE.
>
> http://www.postgresql.org/docs/9.1/static/sql-comment.html
The pgAdmin app lets you enter text in the "Comment" field of a table or column's Properties dialog.
--Basil Bourque