I still swear by Cloanto's Amiga Explorer. While not 100% in the Windows shell extension department--e.g. F2 doesn't initiate a rename, it doesn't fail gracefully on connectivity errors, that sort of thing--it still kicks all kinds of ass and is a snap to get going. I'm especially fond of the transparent access to ROM and disk images.
But yes, tech like UPnP would be fun on the Amiga, although as previously noted, what would you implement and where? There's likely nothing on the Amiga itself that would take advantage of it.
Not related to DNLA, but I can see value in a library and Prefs interface for Bonjour/mDNS.