This is a cool single-purpose site alert.
It's called Tweet Ping, and it is a gorgeous visualization of all the tweets in the world, as they post in real time.
It also has some cool tracking features at the bottom, like a live tweet counter for each continent and well as hashtag trackers. It allows you to do fun little unscientific experiments like calculate the number of tweets rolling in per minute, and extrapolate that into tweets per hour, day, and year. For instance, for one minute in time, it counted roughly 2,400 tweets worldwide. Do a little math and if the TPM stayed constant, that would total about 1.26 billion tweets per year. People sure are tweeting a lot.
Check it out here.
It's not the first site to visualize tweets live, but it's really well-done. It's sort of mesmerizing, in a way, to watch the world light up, gradually, as people tweet.[http://franckernewein.com/ via reddit]