One of the pleasures of using OS X at this point involves the availability of some clean and innovative applications that often spring out of tiny operations that have tight connections with their users.
Apple's Dave Hyatt publishes a blog that is something of a public exchange about the development of Safari. Safari was developed from an open source core and a few of the folks on the small team (my understanding is they number five or six) have strong roots in the open source movement. To suggest that Dave and his coworkers are responsive is an understatement. I have emailed comments and suggestions and frequently get replies back within a day or two. The user community seems to have a fairly tight coupling with the authors and the rate of progress has been amazing by most standards.
Another tool that seems to work better than any of its competitors (on OS X or any platform) is NetNewsWire by Brent Simmons. Brent not only has a great product (I find that extolling the virtues of rss aggregators tends to go flat on people who aren't using NNW), but he responds to bug fixes and new feature requests with amazing speed. This software is good enough that you might want to consider a Mac if you don't have one - it will change the way you view the web.
Notebook from Circus Ponies is another piece of clean software. At first it seems undistinguished from several other organizers, but you begin to learn that it can handle almost anything you throw at it and it is extremely simple. The company has two people. One can go on with a dozen other cool products that, in some cases, have defined niches.
I find this theme of simple innovation very refreshing - there is even a bit of excitement in the community. There are enough successes from very small operations that others are encouraged to try. OS X now has a large enough audience (7 million) that it is possible for a small/clever company to make money - one very slick $30 app I know of has sold a bit over 40,000 copies in the last year - not bad for a two person company that only sells directly through downloads and advertises through word of mouth from enthusiastic users. They are unlikely to grow to 400,000, but that doesn't seem to be their point.
It is amusing to hear the argument that you need to write for Windows to get the scale necessary for survival. It may be that a hypercompetitive market has some serious barriers. First you have to get the attention of the mob (which isn't cheap) and fight off competitors. Then you have to deal with configuration hell - something that is a formidable task in many Windows applications. Another small company I'm familiar with has 2 programmers, two people doing marketing and sales and three people doing configuration testing and support.
There may be a relation between total market size and the size of a company that can survive (of course if it gets too big or too clever Microsoft will pick it off). There also may be an effect that people who spend $1500 on a computer might be inclined to pay for software (some surveys show that people who buy $600 computers don't buy software - it is stolen, "borrowed" or just never installed as the user is only interested in basic functionality*). What ever the case the necessary size of a company required to create and support a given application type may be much smaller in the Mac world than the Windows world. It may well be that the best platform to introduce something innovative on a shoestring is OS X.
* I came across some figures about a year ago that suggested people who spend less than $700 on a home computer tend not to spend much on software - to the point where a sizable fraction will not install any software during the life of the machine and another sizable fraction will only use pirated software and freeware. A third major group only buy one software package a year -- tax preparation software. These groups basically don't have a need for other expenses (many of them are paying for net access and printer ink which are non-trivial expenses).
There was a point where computer users tended to buy software - it corresponded to $1500 PC prices. As the purchase price went up, so did the amount of purchased software and services.
One quote in the article was something like this:
You don't find GPS mapping systems as options in $10,000 cars ... in fact you don't find much in the way of anything.
None of this is suprising (I hunted for a link and couldn't find it -- if anyone sees something like this please send email as I would like to quote the real numbers).