A cursory web search for ways web applications can respect Do Not Track browser settings, found this article on Postmark
Your site is not your product
Rather a website becomes part of your product – one channel or manifestation of it. This point stands out in a talk, still engaging today if a little orthodox now, given four years ago by Tom Coates on the web of data, called Everything the Network Touches. It’s an amusing listen and includes some early breakdowns of the “internet of things”.
The audio is archived at the site for the 2010 dConstruct conference in Brighton.