Lots of good stuff here, but definitely check out Ken Yau's segment (starts at 00:38).
There should be justification for things existing. (1:04)
Thanks to Fiona Cullinan for putting it together. (And to Sulman Mirza for tweeting about it! I missed this when it first went out.)
http://fionacullinan.com/2011/01/content-strategy-18-practical-tips-in-8-minutes/