As a guitar player, it's always been fun to discover different tunings. Of course, you always start with the standard EADGBE, from top string to bottom. But from there, there is an endless array of possibilities as long as you're willing to experiment.
There's the Admiral (CGDCBC), Drop A (AEADGC), Double Drop D (DADGBD), Fourths (EADGCF), and so on. (Thanks to How To Tune A Guitar.net)
Each tuning gives your guitar a different sound and a different feel. I can't say I've really tried too many but the standard tuning has never really been my thing. I've always looked for something different. (And not too different I suppose, I stick with something that is still pretty common.)
Since I discovered it I've been hooked to Drop D tuning. It's achieved my dropping the low E string down a step to the low D note. (DADGBE) With this tuning it's so easy to play successive power barre chords by barring and strumming the top three strings. It achieves a heavier rock feel which makes little use of the high strings and favors the low end. I've just always loved the way it sounds and how the chords are played.
Within the past couple of years I've been stuck on a tuning with an even darker feel by starting with Drop D and tuning everything down half a step. (Db Ab Db Gb Bb Eb) I just love how the lower notes resonate and how I feel the range fits my vocals. But at the same time, this tuning has gotten me in a slump as far as my guitar playing skills go. I feel that I've been so stuck on these simple barre chords that I haven't been learning as much as I can by discovering what the other strings have to offer to music.
So I am truly down in the drop D dumps. Though I love the sound, I've realized that there is more to playing guitar than just one tuning or one sound. So to standard E I go! Rock on!