Well ... we've strayed quite a bit from the original topic of recommending macro lenses for Nikons into an area I feel competent to comment on: Macro lenses in general.
A few things have been said that are in error, misleading or that I simply don't agree with.
Not all digital SLRs have that focal length multiplication factor. Canon makes a couple of full frame digital SLR bodies - Nikon does not.
The definition of macro is life-size or larger. You cannot take a macro photo of an entire dragonfly - they are larger than the sensor of a camera! You can use a macro lens to take the photo, but it will not be at 1:1 magnification.
100mm macro lenses on a Nikon 1.5x or Canon 1.6x crop sensor is not too long! At times I use a 2x teleconverter with my 100mm macro lens on a 1.6x crop factor body to get farther away from a subject. That's 320mm! This link leads to a photo taken with a 3x teleconverter on a 100mm macro lens used on a 1.6x Canon body - 480mm!
http://www.jbs-blog.com/?p=72
Canon's macro lens offerings are 50, 60, 100 and 180mm - Nikon's are 60, 105 and 200mm. They seem to think that long is quite usable.
Macro without a tripod?!!!!!! Only for a record shot of some unknown insect maybe. I always have my tripod and remote shutter release when the macro lens is mounted.
Auto focus when shooting macro?!!!! Once again - not me! The depth of field of the focus is so razor thin most of the time that manual focus is the only way to get it exactly where you want it.