Feasible TeX projects to get started with (expl3?)

I’m a pretty decent LaTeX user in the sense that I write LaTeX documents all the time and I can do pretty much everything that I need to do (with some occasional help from you lovely people). But I don’t know much about plain TeX and TeX’s inner workings, and I don’t need to know it for most of what I do.

I would like to learn more though, and I can’t get motivated unless there’s something actually useful for me to do with it.

So I was hoping you guys would have some suggestions of stuff that has to be done, so I can learn what’s necessary and do it. Something actually useful for the TeX community, but simple enough to be a starting point (it can be challenging, though; that’s the whole point).

I also wanted to know more about LaTeX 3, so I was thinking maybe something related to expl3 could be nice. Even, like, a single function that needs some work, and I could try to give it a go. Anyway, something to make me feel like I’m doing something worthwhile while I learn.

Even better, if you guys are feeling up for it, would be a whole set of progressive tasks, like:

Easy stuff:

• Write this function
• Fix this problem
• Document this code

Harder stuff:

• Add this feature

And so on…

If there were a list of enough tasks that need to be done (even if they’re those annoying parts everyone’s procrastinating), maybe more people would be interested in tackling them too, and it would make it more interesting for people to learn stuff while at the same time helping current projects.