I think it worthy of mention here that not all tifs are 8 bit. True, the tif file in the D100 or D1X is 8 bit. However, when you open that file in NC or Bibble and then send it to Photoshop it will be a 16 bit file in Photoshop.
Other than the fact that it is readily opened by a number of graphics applications I can see little reason for shooting in tif mode but there can be numerous reasons for saving the opened NEF file in tif and I can not think of any reason not to do that. I personally prefer to save my processed image in Photoshops PSD format which limits me to working in Photoshop in the future but I am content with that limitation.