As it is right now, the find function allow us to hide or show some fields. It would be nice to give us some more control.

{comments: true, title: true, summary: true}

will show those 3 field for each matched document.
Let say we have front page that display the last 20 pages and their last 3 comments. We don't need to load every comment of each page.

So instead of the true parameter, we could add some criteria.

{comments: {$limit: 3}} would limit to 3.

here are some operator that could be used to manipulate to filter the returned tree.

$limit
$skip
$sort (though the actual sort could be used instead)
$gt (greater than)
$lt (lesser than)
$eq (equal)
$regexp
$like
....