At my current gig, we use SiteKiosk which locks windows down tight. It uses the IE WebBrowser control via ActiveX/COM/.Net/however the hell it works. Its basically IE but slightly shittier due to there not being a 1:1 between it and IE proper. SiteKiosk has some pretty powerful digital signage features you don't really get from a Windows Embedded scenario. One feature of 8.1 I was looking forward to was "kiosk mode" but with WinRT being blocked from talking to localhost, except through a hack (yes, fuck you Microsoft) it was stillborn for my tastes.
.NET apps are ClickOnce or xbap, which is basically pre-Silverlight. This is the suckiest part. SiteKiosk can run normal applications and Silverlight with no problems but it took SL 5 to get proper COM support and it isn't terribly easy to make your normal .NET library "just work" so that wrapper for a card dispenser isn't as easy to leverage. Due to the low number of these apps (2), we haven't bothered migrating away from shitty xbap.
The largest amount of applications use typical wamp running a lightweight PHP framework and sometimes MySQL as localhost. Some are completely or partially Flash driven applications as well.
SiteKiosk and leveraging IE lets us focus on perfecting the experience though I've become complacent. IE development is just too slow now and testing in Chrome with superior dev tools are absolutely essential. The problem there is we can easily paint ourselves into a Chrome-only corner if we aren't careful.
Leveraging the POS equipment like barcode readers, card dispensers, or printers are the only thing the web proper isn't really suited for unfortunately. This may be where Windows has much more leverage due to their driver model. Most equipment we interfaced with had a .NET library or simple instructions of use with P/Invoke. I saw very little (<1%) that had anything to do with Linux and in typical fashion wasn't something to simply use via something like PHP or Ruby/Rails. Maybe we chose Windows friendly vendors, though, so take this with a grain of salt.