I simply refuse to provide such information. If an employer is using it to screen applicants then it can only be used against me, and I would not likely want to work for that employer anyway. They would expect me to likewise discriminate against people, or give people preferences, based on race, etc. Else, without such information, an employer must make hiring decisions based on experience, attitude, and education – which is what they should be doing anyway.

People’s true diversity comes from their being individuals, though these traits don’t necessarily lend themselves toward easy accounting (assuming one needs to keep records).