I recently came across http://en.wikipedia.org/wiki/Category:Outlines and it took me a while to realize the full extend of this desaster. Some part of en.wp's authors is duplicating Wikipedia, this time without text.
For example, http://en.wikipedia.org/wiki/Topic_outline_of_Algeria is a list of articles somehow related to Algeria. This purpose is better served by either [[:en:Algeria]] (with full sentences) or by [[:en:Category:Algeria]] (with proper software, without full sentences).
My recommendation would be to delete them on sight. Given the situation at en.wp, this is better done with a formal VfD, triple-signed by someone else and already attached objections and specialized templates for revision and arbitration, right?
Mathias