Well, I know nuthin' about theory but I play a couple of what I call "modals"... What happens in them is you get a an eerie mountain music sound out of 'um...
Double dropped D with both E strings dropped to Ds is cool...
Here's one of my own EBEBBE (starting from the high E to the fat E)... If you tune to this tuning you'll leave yer geetar in it for a month...