I've seen a few posts around here requesting/begging/demanding Let's Encrypt support in pfSense. I too have an interest in it but the official client is a bit of a beast. However, it's not as bad as it looks.
See: https://community.letsencrypt.org/t/list-of-client-implementations/2103 There is ton(ne)s of code out there implementing the ACME protocol, including libraries for those wanting to roll their own. Personally speaking I find the official client a bit too heavy going but projects like: https://github.com/srvrco/getssl, https://github.com/kuba/simp_le and a few others have the right look about them to me. https://github.com/Neilpang/le even mentions pfSense in the issues and may work out of the box. At 1300 odd lines of code it isn't that light though!
There are several use cases on pfSense that would be great to see integrated centrally: GUI (obviously), and many packages that are internet facing such as HA Proxy.
What do you think?