Flight Aware - Want to see all the airplanes above you right now? Check out Flight Aware, there might be more tons of metal crap flying above your head than you think.
Blitzortung - Lightning strikes as they happen. Right now Mother Nature seems pissed at Arizona.
California Earthquakes - Just because the “big one” hasn’t happened yet, doesn’t mean mother nature isn’t quietly throwing mini-tantrums under California.
Marine Traffic - Traffic isn’t just on the roads. If you plan on hitting the water with a large vessel (don’t say that’s what she said) you’ll probably want to consult this website. Here’s an example of traffic around New York where there’s a lot running through a pretty tight space (...don’t say it).