I know there is a template in the 2006 version of the Insider's Guide. (I clearly have an older version, as that was from my first year applying! ) I would think the more current versions have it as well, but not sure there!
Would anyone be willing to post a few tips for emailing a POI? What time of year is best to contact them? What should you say to them, or what should you not say? Obviously, showing an understanding of and interest in their research and explaining how you think that your interests would be a good match would be desirable. I would be interested in a discussion about contacting POIs. It can be intimidating and feels awkward when you don't know them. Maybe even if you do know them.