parodies

Websites

Of course, the Onion Network parody website has also a "news" article to this topic called: "Project Manager Leaves Suicide PowerPoint Presentation"

Another great site is The Gettisburg Powerpoint Presentation that tries to make some of the most often mistakes.

Videos

A good point to start funny videos is nearly always to do a search on popular video hosting sites, e.g. Youtube.

Adam Cook, aka The Fightin Analyst, produced the following short video showing many different "horrible" usages of graphics:

Of course "the classic" of Don McMillan should not be missed on this list as well: