https://www.inculcate.me/ – Dead link
Wayback Machine: http://web.archive.org/web/20140811095312/https://www.inculcate.me/
Originally it was a small project to get me off Udemy after they screwed me over and were selling my course for $9 instead of $29 to boost their user base at my expense. Eventually I found out that nobody used any of the features except the buying and downloading, so I just killed it and wrote Paydiv.io instead. That site now does everything I need and runs way better.