New favourites of mine:
D A D F# B E
Nice for playing acoustic fingerpicking stuff with bar chords and slides, writing a ton of stuff in this right now.
Another favourite:
Not so much a tuning, but a capo on the 4th fret (from the bottom of neck up) so it frets every string except the low E, and then tune (what would normally be) the B string up half a step.
Obviously you can tune every string up 2 steps and the B up 2.5 steps but it's a lot easier with the capo, + the smaller frets at that distance make fretting chords a lot easier.
Although if you were so inclined to tune up, you can tune it as:
E C# F# B E G#
If you have light enough string gauges/are game to play with that ridiculous string tension.
Edited by progkidjoel - October 18 2011 at 06:15