I would think that vacuum cleaners are the prime example for household robots at this time? As an IT guy who nevertheless has zero desire to buy anything "geeky" for myself, still prefers analog dials and controls, still doesn't own a smartphone, those also are the only ones I could find a use for in my own home (but at this time I still vacuum manually). People with a lawn might be interested in robot lawn mowers, I don't know if they work as well as the vacuum robots (I imagine there might be a power issue) but if they do that too sounds like a good use. Same for swimming pool cleaners.

What I would really pay a lot for: Small hunter-killer robots to hunt insects in my home!

A bunch of small robots equipped with night-vision and some tiny weapon(s), mechanical and/or laser, crawling around catching bugs. Sure, spiders do that too - but I really, really don't want to live with (actual) spiders. It's psychological. A few well-armed mechanical spiders for bug hunting would be nice. I had bed bugs once, if I had had small insect hunter-killer robots well-equipped with sensors to see them crawl to me at night it would have been a godsend. Anyone producing something like that that actually works, you'll make billions! And it really doesn't have to be all that intelligent: Think about it, mosquitoes, bed bugs, they really don't have much of a brain, and how well they work. It should be doable to build robots that can compete with that low level of intelligence.