Knife Project is pretty cool. It is part of the tools added to help with creating models for 3D Printing, but obviously useful or modeling other things also. Other stuff for 3D Printing: Print Toolbox Add-on Ruler and Protractor
http://www.blendernation.com/2012/06/04/non-blender-3d-printing-in-steel-silver-ceramics-and-rubber-like-material/ New shapeways materials, also a new shop where you can sell your designs! Pretty interesting.
There was a script made for 2.43 that could do this, though you cant dock it anywhere and you have to run the script every time you want to find the tri count. I will post the code here as the i cant find anywhere that hosts it anymore. Maybe the code would give some pointers to people wishing to develop a new version?…