The Mac mini is the little computer that could. Personally, I own four of them -- of various vintages -- and they're all in use on a daily basis, some of them seven years after their initial purchase. They're insanely reliable, super affordable and some of the best kit Apple has produced.
Macminicolo built a company around hosting Mac minis in a high-end data center, providing co-located servers for their customers. Starting at US$35/month, your mini server is given a static IP, fast network access and service options should things head south with your little server.
Over at the Macminicolo blog, the company has posted a few thoughts about the used Mac mini market, and why these systems retain so much of their value over time. For example, they write, "You could purchase a mid-range, quad-core Mac mini for $799, use it for a year, then sell it for around $715." That's a really amazing retention of value.
The post discusses why the Mac mini offers such good value retention, with its continuous brand identity, easy shipping and general capabilities. Compared to the iMac, the mini provides a much easier solution for embedding and tucking away.
It's a fascinating post that you'll probably want to hop over and read in full. I'm throwing open the comments here, so you can (civilly!) share your mini experiences.