An oldie, but a goodie: an Asteroids clone that figures out which domains you've visited: http://t.co/5ceqUllNEg
miniblog.
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Friday's xkcd is painfully true. https://xkcd.com/1785/ (I once visited a Google office in 2012 and hit a Gnome bug with IPv4+IPv6)
It was a smart person who decided that a:visited and a should be different colours in the browser stylesheet. Usability win by default!
There's something slightly creepy about 'you have visited this page 6 times'. It's not a useful metric.