The other day I had to sell a car (details redacted). I did what millions do every day, posted it on the venerable Craigslist. Within an hour I had several calls of interest, and within three hours the car was sold, cash. It is possible it was priced to move, but still, that's impressive.
Even as impressive or more so is Craigslist itself. It exists as a simple HTML website, a throwback to the mid-90s. I'm sure it runs on LAMP*, is rock solid, and can handle millions of concurrent users on crappy old hardware without breaking a sweat.
I love it, and not just because it could help me sell my car in a few hours. To me this is true design elegance. Long may it wave...
* LAMP = Linux, Apache, MySQL, Perl