One compelling reason to not date your articles is that age sometimes destroys perceived value even if it doesn't destroy actual value.<p>For example, I have a bunch of stuff writing about customer service written in 2006/2007.  That field has not evolved so much that "Don't curse at your customers" is bad advice in 2009.  However, if one of those were posted here, the first comment would likely be "Dude, mark in the title this is from 2006", because the audience here is socialized to assume that the new and shiny is what they want to be exposed to and the old and crusty is largely not valuable with the exception of a few classics.<p>I have sites where I have no visible dates for exactly that reason: I intend the content to be evergreen, and if it is evergreen you don't need to know what year it was planted.  (Edit to add context: elementary school teaching activities.  I am not a textbook publisher so I have no incentive for ripping up my multiplication activity every year and coming out with New Shiny Multiplication 2010 Now With Numbers You Totally Couldn't Have Multiplied Last Year!)