Seriously though, datamerge rocks my world. I've never had to use it before with InDesign, but then I was asked to help with yearbook and do student ID cards. This is the opposite of a rant. Perhaps we need a community called designpraises?
I seem to recall this being a topic that is commonly asked about, so I thought these links would be useful for those of us who might be encountering a project needing automation for the first time.
Tutorial on Adobe.com Another nice tutorial with good screencaps Fun YouTube tutorial with Russel Viers