Most appliances you use at home are pretty 'open': one vacuum cleaner is exchangable for another, and so you have a lot of options there. Same goes with ovens and pretty much anything else. I like it that way.
In our household, we have two notable exceptions. Both of them are coffee machines.
I bought klik a Senseo many years ago, because she likes coffee and I don't, and it turned out that she never drank coffee at home because it was such a hassle to produce a single serving. I felt bad about that, and I got her a Senseo. The Senseo started out as a cooperation between Philips, which made the machine, and Douwe Egberts, which produced the coffee pads. It's been closed off with lots of patents, but apparently both producers of machines and pads have been able to get around that -- these days you can get pads from lots of different suppliers, and there are some options for machines. It's "open enough" in that not one supplier can corner the market and dictate its terms.
Yesterday, I bought klik a Nespresso machine. A De'Longhi Latissima, to be precise. Nespresso is amazingly closed: there are several types of machines, which are made by different manufacturers. However, some models are made by multiple manufacturers -- which means someone else made the design and licensed it to others. In this case, the machine is made by De'Longhi, but it is Nespresso which gives out the serial number for the machine!
The capsules are only available over the internet or in specialist boutiques -- there is no trade in the cups that is not directly controlled by Nespresso itself. And everything is tied together through their own backend database. We went to Arnhem today to get some capsules to tide us over the weekend. The lady behind the counter saw that we had ordered over the internet yesterday, and commented on it. After the sale, she asked if we had any questions about the system and whether we wanted a cup of coffee at their counter -- pretty slick. But Nespresso knows everything about what you do with the machine. It's a tightly controlled monopoly, and every aspect of the product is regulated.
I hear the coffee is pretty good, though.