Holiday lights, for sure.
For my landscape lights because the (outdoor) places where the transformers live are not well-suited to Z-wave receptacles (and the Z-wave plugs fit in the transformer enclosures).
I have one on my cable modem to reboot it remotely or by automation.
I’ve used them as instant temporary repeaters when I’m in the middle of moving things around.
I don’t use them for high-wattage devices because I’ve seen how most of them are built. In the one case where I’m tempted get over that, my kettle, I’m worried that sooner or later I’d turn it on while empty and then have to rely on the kettle’s safety devices to prevent my house burning to the ground, and I’ve spent too much time around things electrical engineered for cost and built in far-way lands for that.
If I didn’t own my house (i.e. renting), I’m sure I’d use them a lot more.