What are some good projects to work on in an effort to learn (or relearn) C? Ideally something akin to the assignments one might get in a class at university. Links to actual assignments/project specifications that are available online would ideal.
Note: they don't have to be assignments specifically from a C class or anything like that. Just the type of thing that would lend itself nicely to be implemented at a low level. Learning other interesting things at the same time is bonus!
If this question has already been asked somewhere, please point it out to me. The search terms I tried (class, assignment...!) weren't conducive to my searching as you can imagine.