What I've noticed is that companies could have their public-facing sites on a number of different platforms, but once I sign in to access their real services, I see plenty of these still running on that obsolete platform called "ASP.NET".
Off the top of my head, I know that ordering systems for dell.com, buy.com, newegg.com, godaddy.com, and unline.com run on ASP.NET. tigerdirect.com and armani.com actually both still run on classic ASP, believe it or not.
In finance, the trading system for schwab.com and account management for chase.com run on ASP.NET.
I just traveled this past week. I flew United and rented from Dollar. Both united.com and dollar.com happen to run on ASP.NET. While on travel, I had to buy a webcam for my parents, so I checked microcenter.com. That site runs on ASP.NET.
This is just from the handful of sites that I've used. I can't believe so many of these companies don't realize they're using an obsolete technology.
ASP.NET websites of some other high-profile companies that I know include: kpmg.com, accenture.com, bain.com (Bain & Co.), bcg.com (Boston Consulting Group), and rbs.co.uk.
ml.com (Merrill Lynch) is still running on classic ASP.
I've also seen plenty of government sites running on ASP.NET: defense.gov (US Department of Defense), navy.mil (still on classic ASP), marines.mil, uscg.mil (classic ASP), sfgov.org (City and County of San Francisco), and sccgov.org (City and County of Santa Clara, of all places).