Pretty much all embedded devices smart enough to support TCP/IP, as well. I'm pretty sure that my router is currently the most 'IoT' device in my house, though also the least conceptually novel.
There are some honestly interesting, tricky, and (at least partially) novel problems in 'IoT'. Making devices that are networked, can talk to each other, and actually do something useful with that ability is a real challenge. Even more so if you want compatibility between multiple vendors, support for use cases the vendor didn't more or less build for you(ideally without requiring that the user be a software engineer), or some semblance of assurance that there aren't a zillion security and privacy issues, innumerable covert channels, and other disasters.
My apathy is mostly derived from the fact that most 'IoT' doesn't actually seem to be doing much of that. Plenty of stuff that lets you use the internet as a very long serial cable to connect to its config interface(which is fine, the internet is a great way, if secured, of very, very, cheaply connecting from arbitrary distance; but brutally non-novel), some walled-garden 'ecosystems' that support very limited interaction of devices between two vendors who have explicitly agreed to cooperate and updated their products to make that possible; but otherwise it's mostly the same old IP-capable firmwares that devices expensive enough to have the capability have used for at least something like two decades. Useful; but not terribly new, and often implemented so badly as to be a liability.
It's honestly a trifle disheartening. While arguably in need of some serious maintenance(especially the 'security' of the earlier versions), SNMP is arguably closer to an 'IoT' design(pretty much just add the ability for devices to advertise their MIBs to other devices on the network, rather than having the admin hunt them down and load them, and you are closer to being ready than most actual products are). That isn't really a flattering thing.
SNMP is quite useful; but it is a bit crufty and conceptually ancient. The fact that everyone's shiny, new, 'IoT' things, with their markedly-more-capable-and-way-cheaper embedded hardware typically can't advertise their capabilities and manipulate one another in some vaguely sane way at the same level as some seriously old hardware is not terribly impressive.
Even if the actual implementation is some XML-soup-and-'cloud'-bullshit horror, conceptual parity or superiority would be nice to see.