Pound for pound the best value for a machine running Mac OS X right now is the Dell Vostro A90 netbook -- which is on sale for $199. That's right, for less than the price of an iPod touch you can buy a machine that runs desktop-class Mac OS applications and a Web-browser with Flash.
The Vostro A90 is Dell's business equivalent of the Mini 9, the perfect hackintosh platform that I've written about here before (ad naseum). It's 100 percent the same as the Mini 9 inside, the only difference is that it comes in an all-black enclosure, as opposed to the Mini 9's black and silver styling, and according to posts on the MyDellMini forums it has a little more metal inside making it more rigid than the Mini 9.
You still have to purchase Mac OS X and there are compromises that come with any netbook (Atom 1.6 processor, small keyboard, screen and HDD) but pound-for-pound it's the most bang for the buck of any Apple machine bar none. While it won't win any races running Photoshop, Final Cut Pro or Logic, it runs most other OS X applications very fast and performance-wise it blows the iPod touch away.
In fact, it's so cheap that Apple should cede this market to Dell and work on an OS X tablet/bigger iPhone because there's simply no way that Cupertino can compete with a $199 netbook. Game over.
If Apple's planning on releasing a $500-$600 netbook, as has been rumored, it'd be better off working out a deal to license Mac OS X to the likes of Dell, Acer and MSI than to try to compete with them in the low-cost space. Apple simply can't do it.
Apple needs to focus on what's working and that's the iPhone platform. It's white hot right now with 25,000 app choices and almost 1 billion apps sold. Why on earth would Apple want to get into a race to the bottom with Dell?
Update: The $199 price was a promotional price. Dell raised the price to $250 four days after I posted this piece. [poll=174]