I have done some analysis on the technologies in use by the Alexa Top 1 Million Sites.
Winners (by Popularity)
Apache
PHP
WordPress (over 10% of the Top 1 Million Sites)
Jquery
Google Analytics
Microsoft Word <— as a web editor, come on!! 
Full details here - Web Tech 2011 Report
A second part of the report was also produced examining the Forbes 1000 Top Companies Web Sites. Winners in Part 2 included… IIS, ASP, JSP and Hosted Mail Filtering.
Can you point me to any similar studies (apart from the obvious - Netcraft Web Servers)?
Comments, criticism, observations?