There are some niche phones with a thermal camera, would love to see more of that. Thermal modules are getting smaller, cheaper and better all the time and the main producers like infiray or guide are offering modules that seem to be clearly targeted at the smartphone market.
I'm still discovering new uses for my thermal camera and I wish I could have it in my pocket all the time. The obvious uses are finding gaps in your house's thermal insulation or finding devices that draw a lot of standby energy. But you can also use it to find studs in your walls, find things that have recently been used, like cars in a parking lot or chairs in an office.