Respectfully disagree
With no offense to mini fans, I think its past time to put the Mini to bed.
I never saw much value in the mini over a entry level I-Mac. So it's great you can use your existing monitor and such, but for a few hundred more you can greatly upgrade specs and have a flat panel display.
I think the mini is a brilliant idea by Apple, and it will never be a major seller. But it fills 2 niches perfectly, both of which make Apple money.
1) People with very modest computing needs - perhaps people who are only recently entering the digital age (some people's grandparents, for example) who just want to do email, surf the web, do online banking, check out the travel hotspots as they spend their grandkids' inheritances, etc. The mini is a very non-threatening technology. Probably someone they know has given them a used monitor, they've bought their own keyboard and mouse, and they are set. They like the idea of a Mac because they have heard that their bank accounts, etc are safer due to the lack of virii and other bad things. Apple doesn't spend a lot supporting them because the friend or family that set them up is acting as tech support. Apple may not be making $millions off them, but they are now Mac customers, who might pop into an Apple store and buy their grandkids iPods, or iMacs for school. Big profit makers for Apple.
2) People like me. I need a Mac for professional reasons, and I like to buy computers that will last me 3 to 5 years. An iMac isn't going to be the one I get - but since I am newish to Apple, and patient, I got the mini as a stop gap (I actually started with a 12" iBook for fun - but realized I needed a desktop system). I get to start collecting the software I need and that will transfer over to the Mac Pro - and I get some time to figure out exactly what kind of Mac Pro I need and when to buy it. If the mini wasn't available, I likely would have had to get the iMac and it would have delayed the my Mac Pro for at least 3 years - it too expensive to be retired sooner. The mini is transitional for me. And I can justify retiring it from professional use after only a 1.5 years because it was so affordable (for a Mac). It will continue to be used as a music hub and will become a 350 CD jukebox, so it will still be useful and productive. The iMac would have been too big for this.
I was able to switch to Apple because a lull developed in my business, and I could make the switch without too much workflow disruption. The mini I could buy on a whim (because of the price). I already knew I wanted to move to a Mac, but I didn't know which one. The mini was good enough - and I'll be adding to Apple's profit line next year.
The mini is a brilliant niche machine. It doesn't appeal to everyone, but I believe it appeals to people that are important to Apple.
Plus, my wife converted to Apple when I promised to be Tech Support for her. She got a MBP (another profit maker for Apple) and loves it, and works it hard, and will be needing another one soon. More profit for Apple because of the mini.
I hope they continue making them, though I probably won't ever be getting another one.
Just my 2 cents worth.