We are all mostly familiar with just Windows, Linux, Unix (along with all the Unix derives) and Mac OS as the primary Operating Systems available. There is a whole collection of operating systems out there, ranging from the amateur hobbyist's take on conquering the OS world to full blown systems which either found a niche market or got doomed to oblivion. I shall attempt to present a small sample from this varied and interesting set. From the Un-Distinguished Lecture Series (http://ws.cs.ubc.ca/~udls/). The talk was given Feb. 9, 2007