I have to admit…
… that writing this second part of the answer was WAAY more complicated than I expected.
I’d thought I would just pull together a few examples of different geo-resources, write a quick and snappy post and call it a day.
The more I dug, the more I found. (The irony is that I should have known better—when I’ve written about geo-information resources before, it ALWAYS takes longer than I expect. See: Finding the shortest and flattest route or Mapping the discovery of the sea cow and the blue jay.)
So I shouldn’t have been surprised by this outcome. The bottom line is that there are LOTS of geo-information resources out there. Here’s my initial cut at the major categories that I found.
1. Map resources – maps of all kinds, many interactive
2. Geo-data visualization tools – interactive maps that let you see information of various kinds on a map (or in the form of a distorted / colorized / annotated map).
3. Professional mapping tools and data – there’s a very large number of professional data resources and tools to manipulate them.
Methinks we're mostly interested in the first 2 (map resources and geo-data viz tools). I love professional GIS (geographic information systems), but it’s a little outside the scope of what we want to do in SRS.
Let's look at the first two a bit more...
1. Map resources: The obvious ones are Google Maps, Google Earth (the app), Google Earth Web (the new web version of Google Earth), and associated parts of the geo-resources at Google such as Google Street View and Google Earth Time Lapse. There are also the Microsoft versions of these: Bing Maps, Bing Maps Aerial (like Earth), and Bing Streetside (like Street View). And there's more! Note also that Yandex has a map, as does Tencent (the Chinese company) and Baidu (the Chinese search engine). LOTS of general purpose maps out there.
They each have their strengths and weaknesses. Tencent maps is great in China, but has little coverage in the rest of the world. Yandex maps is also great in Europe (but shows Ukraine as part of Russia). In general, maps show the political beliefs of the country of origin. (Check out the boundary of China in the South China Sea; other countries don't necessarily agree that this is the extent of China's territory.)
|Not every country agrees that this border is the actual extent of the PRC. (Esp. the part that runs down into the South China Sea.)|
Likewise, you can make an interesting comparison with these two maps of downtown Warsaw. If you look carefully, you'll see some differences in what makes it onto the map.
Yandex' map of Warsaw, Poland.
And Google's map of the same area, which has a lot more commercial entities on it.. and fewer bus stops.
For me as a SearchResearcher, the value of all these different maps is that I can get very different views of a place. That's particularly useful when you're looking at places that some people want to be un-photographed. Sometimes one service has it in clear view while another has it obscured, as is the case with Ingolstadt Airport, Germany. (Note to the reader: Here it's one way obscured; there are places where it's the other way around.)
There are a LOT of general purpose map resources out there. Here are a couple that I like:
Wikimapia - a geographically indexed kind of Wikipedia. (Although it's not part of Wikpedia.) Handy for looking up things you can see on the ground (or in an aerial image) and figuring out what they are.
Open Street Map - a map that's created by the users. Lots of different layers (e.g., "Humanitarian" and flexibility in creating different kinds of maps.
You can find more by doing a search for: [ Wikipedia ] and then skipping down to the section called "See Also" (I've used this trick to find many other fascinating mapping services).
Speciality maps: In addition, there are LOTS of specialty maps that locate on a map, sometime in real-time, as with this map that Krossbow suggested showing live lightning strikes at LightningMaps.org (shocking!).
Often you can find such sites by searching. Example:
[ maps lightning strikes real time ]
you can find maps of wildfires, road closures, tweets, and so on. Jon-The-Unknown pointed out this great Marine Traffic map, here showing the marine traffic near Vancouver:
And we've talked before about various air traffic maps, such as this one from FlightAware.com -- here showing the live air traffic around San Francisco airport.
And, of course, most spreadsheet systems (certainly Microsoft Excel and Google Sheets) both make it very easy to create simple maps of states or countries showing different kinds of values in spreadsheet cells. But we'll talk about that another day!