Reminded of when I was playing with
raw X11 protocol... I eventually wanted to build my own X server but quickly found that was way, way too ambitious. (and that mainline X.org already had SDL support anyway.)
---------- Post updated at 10:56 AM ---------- Previous update was at 10:26 AM ----------
Really though, many of those 'specials' are interesting examples, if useless as is; a solaris device driver, A PAM authentication module, graphics in PERL, a tiny illustration of Dtrace...