The existing boards assume that people only have questions. I don't have much to offer myself. The only thing that comes to mind is creating a customised theme for Xfce - I really was not taken with the theme provided, so I adapted two or more to create some of my own. Xfce isn't commonly used so that would be of little interest but I believe other members would be able to offer some mini tutorials.
I know you have a wiki but wikis are about as popular as graveyards. I've never posted to a wiki because (1) I feel I don't know enough and (2) I doubt anyone will ever read what I write. Even a wiki with a specific theme such as a particular distro attracts little interest. The outstanding exception is Wikipedia but note that it is an exception.