I don't have an example for this but I was just wondering if something like this is valid in any situation:

SELECT somefield
FROM sometable
WHERE something1 IN (SELECT somefield2 FROM sometable2)
  AND something2 IN (SELECT somefield3 FROM sometable3)

Yes. Your syntax needs to be fixed though:

SELECT somefield
FROM sometable
WHERE something1 IN (SELECT somefield2 FROM sometable2)
AND something2 IN (SELECT somefield3 FROM sometable3)

more