Every country with at least one public cam, grouped by continent.
Each camera is filed under the country it stands in, not the country of whoever publishes the feed. Most of what you find on a country page comes from that country's own road, river, port and weather agencies, so the mix says a lot about what a place monitors: motorway junctions in one country, dam levels and snow gauges in the next. If the view matters more to you than the place, the category pages are the faster route.
Picking a continent first works when you know roughly where you want to look but have no country in mind. For the opposite approach, the Surprise button opens a random cam from somewhere you would not have thought to search. Note that a few agencies serve their images only inside their own country, so a cam listed here can still refuse a viewer abroad.