Example for the first link: <area shape="rect" coords="0,0,67,21" href="index.html">
TBH, I did not know this is something which can be done in HTML but that got me curious on how it ended up on PG's blog given many limitations it has :)
[1]: http://paulgraham.com/ [2]: https://i.imgur.com/uo254ts.png [3]: https://s.yimg.com/aah/paulgraham/quotes-1.gif