PoWH Coin - The World's First Autonomous and Self-Sustaining Pyramid Scheme
https://powhcoin.com/index.html
The site is setup as a joke and social experiment but it actually can make you money. It does warn you that you'll probably lose money, but it's an interesting idea and I've personally dropped £200 on it and saw £5 dividends in one minute.
Even if you're not prepared to put money in, it's a really amusing page. Their Whitepaper links directly to the SEC guidance on Ponzi schemes :)
It's worth adding that I'm actually making money from this