It's goofy, but another one is situations where you have a lot of stored heat energy, thinking like pools, hot tubs, hot water heaters, etc— all those things could be activated in response to spot pricing with pretty simple policies (I want a shower of at least X degrees at 7am, I want the hot tub at at least Y degrees by 9pm, etc).
With renewables the incentives for load management become even higher (per this article). The real next step after second-by-second billing would be setting up chargers with backfeeding capabilities/policies, so that you have an arrangement with your employer to charge your car at work on cheap daytime solar power, sell it back into the grid during the evening rush, then charge up again on overnight base load. Most EV batteries are way overspecced for what people need in daily use, so as long as you have a special "charge me to full and stay there" mode you can switch into, there'd be no reason (other than a bit of wear and tear) not to cycle your battery like this.
But for me as a customer, the price was as high as allways.
But if customers could react to that (automatically), you could have all sorts of jobs waiting for it. Bitcoin mining, dryer, charging batteries, freezer full power ... would be good for the grid, too, to balance it.
Texas energy markets are where all the fun on this front is really happening.
I've wanted to have realtime pricing like that for a while, it seems to be becoming available again.
I honestly thought that was what the advanced electricity meter roll-out was going to do; but it seems not.
More direct energy cost to service price charged seems like a good thing in general.