Interesting glimpse of what you can do with a combination of sensors and Twitter. From Tech Review.
If you want to know whether or not the tides are high enough to get your sloop out of Ockway Bay in Cape Cod, you could consult NOAA's tide tables. Trouble is, less'n you're a pipe-smoking old-timer who's handy with the lobster cages and a sextant, they're as likely to get you stuck going in and out of the bay as they are to tell you, with sufficient accuracy, whether the already-shallow draft below your boat is enough to let you safely navigate the muddy shoals of your home port.
That's where the internet comes in, and not the kind that's stuck behind a desk, twiddling with an iPad – we're talking about the Internet of Things. Using an ultrasonic level sensor to bounce sound waves off the sea surface in order to determine its height, an XBee radio to send that data to a receiver on shore, and most importantly, an ioBridge IO-204 to relay that information to servers in the cloud, Cape Cod resident and ioBridge hobbyist Robert Mawrey is able to broadcast to his entire community near real-time data on actual sea level.
Actually, in this particular case, the Americans are just catching up. See, for example, the stuff that Andy Stanford-Clark has been doing with south coast ferries.