To export a query as tab-delimited from psql:

\pset format u
\pset fieldsep '\t'
\o filename
... query ...

This creates an array aggregate accumulator which can then be joined into a string. Very useful for combining m-m lookup data onto one line:

CREATE AGGREGATE array_accum (anyelement) (
    sfunc = array_append,
    stype = anyarray,
    initcond = '{}'
);

Here's an example query using it that pulls out ERM information grouped by subject, including the content types which are aggregated onto one line:

SELECT s.subject, em.key, sm.rank, rt.resource_type, array_to_string(array_accum(ct.content_type), ',') AS content_types
FROM erm_main em
JOIN erm_subjects_main sm ON ( sm.erm_main = em.id )
JOIN erm_subjects s ON ( sm.subject = s.id )
LEFT OUTER JOIN erm_resource_types rt ON ( em.resource_type = rt.id)
LEFT OUTER JOIN erm_content_types_main ctm ON ( ctm.erm_main = em.id )
LEFT JOIN erm_content_types ct ON ( ctm.content_type = ct.id )
WHERE em.site=1
GROUP BY s.subject, sm.rank, em.key, rt.resource_type
ORDER BY s.subject, sm.rank DESC, em.key;