Shopify just rolled out free SSL certs for all it's customers. I was curious how they did this, and then figured out it was using Let's Encrypt. Something I've personally never heard of.
Links: https://www.shopify.com/blog/73511365-all-shopify-stores-now-use-ssl-encryption-everywhere
https://letsencrypt.org/2015/12/03/entering-public-beta.html
https://en.wikipedia.org/wiki/Let%27s_Encrypt