Using these tools you can check a whole bunch of live statistics about your countries power grid. You can see how big percentage of the countries power comes from coal, nuclear, wind and more. You can see the current average frequency of the powergrid, how much power the entire country is currently using, etc.
For the US you can even see where the power plants are and what type, where the power lines are and how much power they are transmitting. Useful? Maybe, but certainly quite cool.
You can find the US version here.
You can find the UK version here.
You can find the French version here.
You can find the Swedish version here.
If you want something similar for your own country, just google your country and ‘power grid live status’. Most countries actually have something like this.