If you tune that down a half step you can play some Dashboard songs I think. It wouldn't suprise me if there are some Goo Goo Dolls songs played in open D5, Jonny Rzenik loves drones. Try http://www.alternatetuner.com for chords.
http://www.geocities.com/xulfrepus/guitar/index.html There's a link to a chord generator that has some alternate tunings, but I don't think it has DADADD. You can punch in on the chord name finder 11 0 0 2 3 11 and get DADADD as the tuning, then it'll tell you the name, but that's all I have.