A variation to a dropped D tuning is to take a capo (shubb works best for me) and cover the second fret leaving the top E string open and covering the rest. In effect it's dropped E tuning. Played the same as dropped D. Some capos physically cannot accomplish this feat. You'll have to apply the capo with the open side up. Have I totally confused you yet?
Another alternative method is to take an old capo and cut away the tubing so all you have left is enough to cover three strings. EADGBE now cover the eADGbe strings at the second fret and pick away. You can further it by using the method and add a regukar capo two fret nearer the neck than your altered capo. Or regular capo at the second fret and the altered at the fourth, It's really fun to experiment with and saves a lot of retuning.
There is a companny that sells a product called "The Third Hand" and has movable cams that can adjust each individual strings. Dropped D is nice and these variations are just an extension or cheating way to do the same thing. Good luck with the experimenting. That's when pickin' really begins to get funner.
Mudjack