The Open Build Service could always use a good write-up. Something like a commented step-by-step of how to build a package. There are plenty of how-to's which can be used to write an article like that so it's not even that hard. You will need to use OBS to build a reasonably complicated package, do a submit request and some of the other functions of OBS. You can of course use the documentation and ask people for help! You will need to describe the process, your thoughts and difficulties you encounter. You will learn how to write a technical articles and get some in-depth coaching on how to keep a text interesting and how to keep your audience in mind.