There are actually a great many companies into nano. IBM is probably the most "researchy" but they also are putting it into products. Intel, GE, Siemens, HP, lucent, motorolla, 3M, Dupont, Dow, United Technologies, Samsung, Sony, Nichia, and a host of others have significant efforts in what are broadly called "nanotechnologies." The question is, what area are you interested in? I suppose you are looking for pure plays, and it's true that there are many private companies out there, in the hundreds of companies! What areas are you interested in?
There are several general areas:
MEMS
Particles
Quantum Dots (subset of particles really)
Bionano (mostly applications of particles & materials)
nanofab (smaller than current lithography)
carbon nanotubes
sensors of various kinds
microfluidics
There aren't many that really are making a lot of money. Nano tends to be expensive and you really need to have a device or design that really requires the nano to make it even worthwhile, and as in the case of semiconductor processing, you really need volume to drop the price. Also there is a lot of stuff out there that is less that perfectly reproducible, if you know what I mean, so be really careful if you get interested in a young company started by some guy at a university.
Generally speaking, nano is very young, and of those companies I'm aware of that actually have stuff that works they aren't addressing very large markets, and/or they are suppliers to other researchy companies without well defined products, well defined markets, or both.
I know of a couple of companies with very good technology, that works, and they're run by good people, but they simply aren't able to generate enough revenue right now to go it alone, let alone go public in this environment.
Basically it's a cool area, but it's not ready for prime time. I compare some areas of nanotechnology to chemistry of 100 years or so - seems like we know a lot, but really, what can be done with it right now? Very little, really, at least when you look at how much it will cost to build a business, and that's _if_ the technology is actually reproducible. A couple of areas are probably where semiconductor technology was in the late 60's or early 70's. Still a long way to go. OTOH, the pace of innovation is way way faster right now than it was in either of those periods. However, there remains a lot of overinvestment in the area that won't dry up for several years, and many companies will not survive.
In fact, some of the big companies are withdrawing their efforts (I hear MOT is doing this /has done this) even while some others are really beginning to invest in it.
So, to end my dissertation, I think it's too early, unless you're into angel investing. JMO
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