A map that also shows the difference between winter and summer for day length would be great. It is down right quaint hearing people bitch about the hour of change that DST does compared to the near 6 hours that nature has already taken. (Note, this doesn't require contextualizing to across the ocean.)

Similarly, for storms and such, knowing just how different the east coast of the US is compared to many of the places that people came from is amusing. What I thought of as normal rain is evidently comparable to the gods wanting to kill you. Always amusing when people ask, "doesn't it rain a lot in Seattle" for me. I don't know that I would have called what we get rain.

A beautiful illustration of why solar power is a no-brainer for California or Arizona, but is a doubtful proposition for Germany.

It would also be interesting to see a version corrected for the warmer temperatures due to Atlantic currents. Although that might cause some sort of near-Atlantic or near-Mediterranean "skew" in the map rather than the whole map dropping or raising by some amount, but maybe adjusting the whole map could be a reasonable first approximation.