I came across some pretty cool open data maps recently. The first one is from M&S (via Spencer Wright's awesome The Prepared newsletter), which shows exactly where in the world their products (food & clothing) are made, as well as where they source their raw materials from:

https://interactivemap.marksandspencer.com

Then there's the Open Infrastructure Map that shows where electricity cables, telecoms towers and undersea cables etc. are located:

https://openinframap.org/#2/0/0

I've noticed that there are air pollution sensors installed by our local city council next to busy roads, and checked What Do They Know to find out if anybody has made a freedom-of-information request to get the data. Turns out they are already publishing it online:

https://airquality.gov.wales/