The 55 micro was the first extra lens that I purchased after buying my Nikomat (I had just arrived in Okinawa). I have always loved the lens and macro photography. I also use it frequently for general photography. You must understand that the only automatic Nikon I have is a Nikkormat EL - the others are all completely manual.
I've been using the 105 Micro Nikkor for the past year now. Excellent quality and 1:1 with no extension tubes or attachment lenses. A bit expensive, but worth every penny.
AF is not that fast, but then MF is supposed to be used most of the time.
The good thing about the lens is the working distance, which is large enough not to scare bees and such.
For illumination I bought an el-cheapo ring flash (comes under various brand names, mine's a TOPCON) and have been using it with a reasonable success rate.
I've been using the phenomenal Kiron 105 macro. 1:1 without any adapters or tubes. 2:1 with a quality 2x teleconverter.
Thanks for all the insight on macro photography. I got the lens on Saturday and it's great. Only one gripe: in order to get 1:1 with the 55mm micro and the PK-13 extension tube, the front of the lens has to be a couple of inches from the subject. Not very good if you're using lighting due to shadows, etc. I think I should have gotten the 105mm micro instead. Oh well, I'll deal with it. I'll have some images for the Gallery soon.
I have used the 55mm 2.8 and 105mm f4. Both are lenses of good quality. The 105mm f4 required an f stop of f8 to really get sharp.
If you get a bellows I would very much suggest that you also get adapter ring(s) allowing the use of both the Micro-Nikkor and your enlarging lenses to be used in the ordinary as well as the reversed mode. The reversed mode for 55mm threads will also allow use to use any lens with a 55mm thread reversed. For example if you wish to get a lot more magnification than is allowed by the Micro-Nikkor a reversed 28mm for example will allow you to do so and may give extraordinarily good results. If your interests, in the future, lie in really extremely large magnification than reversed movie camera lens can perform nicely. Of course one may use for example Photars and Luminars with great success they can be quite costly.