Who remembers Skytorrents (https://news.ycombinator.com/item?id=13423629)? Posted as a "Show HN" here, it was a DHT-sourced index and stack written in C with no JavaScript, no cookies, no ads, no tracking. Skytorrents was unbelievably fast, friendly, and complete, and this translated into rapid adoption and traffic growth that caused the site to shut down due to server costs after just a year (https://torrentfreak.com/skytorrents-dumps-massive-torrent-d...).

It was a shame that the technology behind Skytorrents was never open-sourced; it was the best torrent crawler and site I've ever seen, and I would have liked to see how it worked so well.