Since a great deal of my music (especially instrumentals) are in altered or open tunings I've included my list, with a few suggestions, on how to approach playing in them. My basic advice is still to compose music that happens to use an altered tuning as opposed to stringing together a bunch of licks that apply to a certain tuning. The latter approach generally tends to sound rather gimicky.

String gauges are also an important consideration when using tunings. For instance, I use a .68 for the low E on my 6 and 12 string, and a .90 for the for the lowest string on my seven string. These heavy gauges are necessary to maintain good bass tone when the string is lowered to C or B or even an A or G as on the seven string. Other modifications include using an Earvana compensated nut on my six string and a custom bridge on my 12 string in a effort to achieve better intonation. I also recommend putting a little pencil lead (graphite) into the grooves of your nut to improve string transit when tuning. Overall action setup will of course vary with the guitar and taste of the player.

All tunings are given 6-5-4-3-2-1

Song titles refer to cuts from my cd, Another Look at the Sunrise,
available at CDBaby.com and Amazon.com

Tunings related to standard

C#-G#-B-F#-B-E
(Good for playing in either C# minor or E major)

E-A-E-G-A-E
(Droney, good for Celtic stuff)

E-A-D-G-A-D
(Good for modal playing in E minor/G major)

E-A-D-G-B-D
(What You're Worth)

E-A-D-G-G-D
(Turns the guitar into a dulcimer)

E-A-B-F-#-A-D
E-A-B-F-#-B-E
(These two tunings are great for new age type
explorations, tapping, smacking, unusual chords, etc.)

E-A-B-E-B-E
(good for modal and bottleneck slide)

D-A-D-E-A-E
(I use this to cover Neil Young's "Helpless")

B-A-D-G-A-D
(try this for playing in B minor)

D-A-D-G-B-D
(classic double dropped D, CSNY, etc.)

D-A-D-F#-B-E
D-A-D-F#-B-D
(Both tunings are great for added 6th chords)

D-A-D-F-#-A-D
(classic open D)

B-A-D-F-#-A-D
B-F#-C#-F#-B-E
(A Second LIfetime)
(Explore in B minor with these two tunings.)

B-A-D-F#-B-E
(as above)

D-G-D-G-B-E
(classic G add 6, Chet liked this one)

D-G-D-G-B-D
(classic open G)

D-A-D-G-A-D
(Pierre Bensusan uses this as his standard tuning!)

C-A-D-G-B-E
(standard tuning with a low C)

C-G-C-G-C-E
(Great slide tuning especially on 12 string, Kottke
used this on 6&12 String Guitar)

C-G-D-G-B-D
(open G with a low C)

C-G-D-F#-B-E
(Great for Lydian mode)

C-G-D-G-G-D
(I stole this one from Preston Reed, very quirky
tuning however)

C-G-D-G-A-D
(Related to DADGAD but with Low C and G)

C-G-D-G-B-E
(Standard tuning with Low C and G)

Seven String Guitar

C-E-G-D-G-B-E
(Standard tuning with Low C)

B-E-A-D-G-B-E
(Standard tuning with Low B)

B-E-A-C#-E-B-E
(Great for rhythmic strumming in E or A major)

B-F#-B-D-F#-B-E
(Great for B minor and two handed tapping)

B-F#-B-B-F#-B-D#
(I use this for slide playing, a little hard to learn
how to play in though.)

B-E-A-E-F#-B-E
(Lute tuning with a Low B)

D-E-A-D-G-B-E
(Standard with a Low D)

C-E-A-D-G-B-E
(Standard tuning with a Low C)

A-E-A-E-E-A-E
(Droney, but also good for two handed tapping)

A-E-A-D-G-B-E
(Standard tuning with a Low A, great for fingerstyle
jazz)

G-D-G-D-G-B-D
(Open G with a low G))

G-D-G-D-G-A-D
(Modified DADGAD with a low G)

C#-E-A-B-F#-B-E
(good for playing in C# minor or E major)

G-D-G-D-G-B-E
(G6th with a low G)