[Whenever](http://www.cbc.ca/searchengine/blog/2008/06/search_engine_heads_to_china.html) someone says “[netizen](http://en.wikipedia.org/wiki/Netizen)”, the first thing I think of isn’t “citizen”; it’s “denizen”.
I just [looked that word up](http://www.merriam-webster.com/dictionary/denizen). I’d always assumed it was related to [den](http://www.merriam-webster.com/dictionary/den), but apparently it’s not.