As an administrator, I would like to be able to see which users haven't logged in in the past X months.

Currently you'd have to perform the following query on the database:

SELECT a.user_name, from_unixtime(b.attribute_value/1000) 
FROM cwd_user a, cwd_user_attribute b 
WHERE a.id = b.user_id and b.attribute_name = 'lastAuthenticated'
AND from_unixtime(b.attribute_value/1000) between '2013-11-05 00:00:00' and CURRENT_DATE();

That would be good if you could also see the details for each user on the screen just like you can do in JIRA: