I like to mess around in Open D (DADF#AD) tuning and have a couple of tunes worked out in it. I actually keep one of my guitars in that most of the time. Also acquired a Kyser Short Cut capo a few years ago and have put together a few tunes with it. Agree that Drop D is used a lot but it's still an alternate tuning and is great for finger style. And then there's Double Drop D for cranking out those Neil songs. I've messed around a bit with open G (DGDGBD) but nothing original has come out of it yet.
Yesterday I found my main guitar in some strange tuning. A quick check of the tuner revealed (C#G#C#C#C#C#). Nothing like having teenage guitar players in the house.