Maybe I missed it but I thing a big one that should be included is:

Acoustic Instruments—Is the music performed primarily on acoustic instruments?

Obvious it may be, but I missed it .. Thanks for the suggestion!

And thanks again Music_phantom :) The samples idea was good. I had already made a similar one, whether or not the band or artist uses breakbeats. Maybe your suggestion is better, I'd have to think a bit.

edit :

Trait : Superfast bass drum

Description : Describes whether or not the drums are (occasionally) played in a super-fast double kickin' fashion

Possesses trait (1) : Gorgoroth
Does not possess trait (0) : Dire Straits

Example :

Yeah I saw the breakbeats, but I was thinking more along the lines of whether an artist usually uses samples, because that category was limited to electronic music. I mean you have DJ Shadow who made an album with samples, plus they are integral to a lot of types of hip-hop music and I wasn't sure if that should be left out.

And another one I think we should really have (I picked weird bands probably but I thought I'd use the two of them because their music is so similar the vocals are one of the biggest differences):

Trait: Female Vocals

Description: Describes whether or not the band has a female singer.

Possesses Trait (1): Kimya Dawson
Does not possess trait (0): Jeffrey Lewis

Example:

I'm not so sure about sex as a trait. Female vocals are defining for the sound so it could be valid, but on the other hand I'm not sure it's a difference I want to group or ungroup bands by. A black metal song may not be black metal anymore if you switch the drums for breakbeats, but it's still a black metal song regardless of what sex the singer is if you know what I mean.

Social & Personal Identity Traits for Music
 

I'm trying to create lists in Pandora - one for Queer musicians, one for Transgender, one for Lady rockers, another for Women of Color, and I want socio/political/personal struggle songs; it's driving me crazy that music will come up that has nothing to do with my desired social/personal identity traits. Therefore here are my suggestions:

1) Gender - female, male, transgender woman, and transgender male
2) Sexual Orientation - Heterosexual, Gay, Lesbian, Bisexual, Questioning, Fluid
3) Racial & Ethnic identity & National identity
4) Religious identity (including rationalists, humanists, non-theists)
5) Social/Political/Personal lyrical content (i.e. love, social justice, poverty, wealth, drugs, sex, mysogyny, absence of mysogyny, etc.)
6) Era/Decade of music

In regards to the identities (gender, race, etc.) of musicians - some may want one or all on vocals or lead vocal with a specific identity (such as African American females), or all members in the band (such as an all-female rock band), or on guitar or another instrument, for example.

This could of course cause some who are racist or homophobic to avoid music they should hear if these traits are listed on Pandora; but not all traits need be listed on Pandora & Pandora only specifies some of the traits for the song. I'm just frustrated with making these lists and I don't even know if transgender musicans are recognized & there's only a few that I know of. I also get frustrated listening to a lot of music about female dependency on a male to be happy, though I do enjoy some love songs. Also, I'm looking for a variety of styles in my music, so Pandora tends to assume that if I have thumbed-up a couple of slow, melodic songs then that's what I'm wanting to hear. I guess there's shuffle, but some of the music it spits out is just NOT what I'm wanting to hear.

Well I must ask what the project is being used for? I have an interest in listening to music from a social/political perspective & I also have a friend who is interested in feminism and race in music & she has served as a music director for community radio - so to both of us, it's important to find women who play the guitar, for example. There's many bands that feature a female on vocals, but for some female guitar-players out there it's empowering to listen to music with a female on the guitar. That's just one example. Perhaps I should be submitting these suggestions to the Music Genome Project. It would help if I knew what this project was for.

Of course, the Music Genome Project is private, so having a listing of social/political/identity traits would be helpful for people working in radio stations for example. There's a lot of great-sounding music out there, but I don't always like the lyrics or I'm looking for Transgender musicians that can empower people who are Transgender, for example.

Of course, "they" as in corporations & the government can already track so much about us based on online activities such as facebook, pandora, etc. so there's always a danger in this but I am frustrated with not being able to hear what I'm interested in on Pandora on the correct channel, or Pandora thinking I'm wanting to listen to sleepy Motown music all day, or other sleepy music. I just want to hear some strong Women of Color singing about social issues of their day and I can hardly find anything good from a social-perspective from the middle of the century, and I imagine there was a lot of good music out there if not in mainstream music then elsewhere and some of it must be on Pandora; I will need to look into the reggae, blues, and jazz of the time. Even then, Pandora sees that I'm listening to Blues and starts playing Blues music. Also, just because I want to hear some powerful songs by Tina Turner after she left Ike doesn't mean that I want to hear them together. From a historical perspective it may interest some, but I'm interested in finding empowering music that also sounds good.

Okay, so I found a couple of fields that may be of interest to me - ethnomusicology and sociomusicology, so I guess I should just send suggestions to the Music Genome Project & maybe they can refer to the research plus add obvious social/ethnic/political traits for those of us in which message & identity of performers matter. And someone mentioned Kimya Dawson - she's totally rad!

Okay, I found 3 African American female singers so far from the Civil Rights Era that I like - Odetta, Nina Simone, and Big Mama Thornton. So that's good for now, but still Pandora thinks I want to hear Eric Clapton & Duane Allman on the same station. The song sounded great, but wasn't what I was wanting to hear.