I post my extras on Patreon. : ) I do sketch-posts, extra sketch-comics between chapters, and semi-regular Q&As. There is a bunch of stuff that goes on behind the scenes with my comic, so it's neat to be able to share it somewhere with people who like the comic.
... I'm also considering adding a semi-regular tutorial and/or general storytelling babble-column thing to my Patreon, because I do so love babbling about my process, and there are people who seem to appreciate it.
I personally love seeing all the work behind the scenes, because a.) I can recognise stuff I do myself, and b.) learn new methods, and c.) just generally get to know the skeleton beneath the skin of the final product, which is neat!