Back in 2012, one of my first open source contributions was to an experimental wiki called the Smallest Federated Wiki. Created by the inventor of the wiki, Ward Cunningham, this project explores the concept of distributed computing in web publishing. Rather than editing a wiki page on a centralized server, each contributer has their own server. To edit other's pages, you fork it to your server.
You'll notice at the bottom there is a list of cryptic little ☼ , + , ✎ , ↕ , ⚑ , and ✕.
These symbols represent a state in the journal of edits of the page. This is one of the features I implemented during my involvement in the project. The left and right arrows help you move from page to page. You can edit your wiki pages by dragging blocks of text up and down and between pages (potentially on different servers).
If you are curious to learn more about how the Federated Wiki works, take a look at How To Wiki.