I've done some C programming in the past (not much though) but thought it would be fun to program C for the Plus CE. However, I can't find anywhere to start. Is there any tutorials on C programming for the CE I missed?

I found this digging through Cemetech via Google

https://www.cemetech.net/forum/viewtopic.php?t=7087

EDIT:
Now that I have read this, I feel like I want to write some crazy, innovative game, as I program primarily in Java and C#. The only thing holding me back (From this and extensive ASM programming) is the risk of erasing your calculator's memory. I might get an Emulator.

You could probably find all the examples and information on the actual SDK page:

https://github.com/CE-Programming/toolchain/releases

Once you get that up and running, there are many tutorials here on Cemetech and on the web for your enjoyment. Also the countless examples in the toolchain as well.

The main thing is to just try building the examples on your own; taking a look at the comments and the function documentations, and seeing what you can create It's all an exploration, but if you have any specific questions, feel free to ask.