What's a good practical but small enough project you can do with C? Typically if you are learning Ruby or Node, people recommend creating a blog. What's something like that for C?
(Yes, I'm in the dive in the deep end learning camp.)
Case in point: Star Control 2, a commercial title with a cult following, which had subsequently been open sourced, then modified to use SDL. Still works all the way from Windows through mobile phones to Solaris, thanks to portable C and the SDL library, and is an excellent game to boot. Original ran on DOS and the 3DO gaming console.
Microcontroller-C is extremely different from application-C but there are many less complicated concepts. Like never having to touch memory allocation or string munging.