Does anyone know approximately how many websites are running DNN? It is over 100,000? I'm trying to write a marketing / position paper supporting the use of DNN. If not it would be an interesting number to know.

A quick Google search of URLs with Tabid in them resulted in over 10,800,000 pages...   so the total number of sites many be greater than 50,000   However,  there is a large number of sites that are not exposed to the open internet.  These Intranet sites are unseen to any google search.   

I had a survey on my site for over a year asking how many people used DNN on Intranet site .. over 70% indicated they used DNN on a Intranet site or on both Intranet and open internet site.    

So,  DNN may be an "Iceberg"  --- I believe there is a larger installed base hidden within Intranets, then exposed on the Internet. 

Also, I believe you will find many of the DNN developers are working on projects that are intranet based or hidden behind corporate firewalls.

Food for thought - Paul.

You can try searching for DNN specific address strings.

For example, Google returns 43800 for "/ctl/Terms/Default.aspx".