What are these other unix?

I was reviewing my blog stats the other day, and I noticed a funny thing.  Just over a third of my readers that day were using 'Other Unix'.  Not really sure what to make of that, I can't remember that last time I saw a Unix machine other than at University.

This isn't a random blip either -   There seems to be a fairly consistent number of other-unix readers of my blog.

I can think of a couple of scenarios here.  Firstly the google spider is running from a unix machine, in which case google are giving more readers than reality.  Secondly I am out of touch, thirdly the Google chromebook might show up as 'other unix'.  This would fit in with the popularity of chrome as the dominant browser.

Any suggestions welcome.