It's not something which you see on first sight, but nano does support syntax highlighting. Have a look in /usr/share/nano and there you'll see some files which define rules for syntax highlighting. Now, to enable C highlighting in nano, edit your ~/.nanorc file and append the following line:

Unfortunately, the syntax highlighting for shell scripts could be better, so that's why I uploaded a better one to this page. It's more aimed towards bash, but I think it's useful for /bin/sh as well.

You are free to use it, but it would be nice if you would mention bugs or improvements.