WebCite.com is a useful tool ... expecially to help students see the power of re-writing before posting

Without websites like web citation and the "way back machine," some people might be tempted to rewrite history.  Historic revision in our times":

http://www.webcitation.org/6D8yy8NUJ

Here are examples of removal of people from textbooks...

Here is an article in Wikipedia
http://en.wikipedia.org/wiki/Censorship_of_images_in_the_Soviet_Union

Thank goodness for WebCitation.com

http://joannenova.com.au/2012/12/death-threats-anyone-austrian-prof-global-warming-deniers-should-be-sentenced-to-death/