It would be very nice if when searching something ddg could also look in my social bookmarks and mix the results with the other ones.
That would be similar to the way Google works with Google Bookmarks
but a bit less google-centric :)
I've played with this idea with some yahoo pipe some time ago, to mix some search results with my delicious bookmarks:
but of course the interface to browse search results here is well... less than ideal :) and the way results from various search engines are mixed together could also be much improved !
Interesting point: only the username is required to get results from delicious's search api for public bookmarks, a usename that oculd be saved among the other "settings" ddg offers.
Of course the future of delicious is not clear, but that may apply to other bookmarking services, I guess.