As the title suggests I think it would be nice to be able to turn on/off shaders, animations, particles and avatar sounds per individual.
I often run around with animations, particles and avatar sounds turned off for everyone but friends and often times someone will have an effect I'm not friends with that I would like to see without turning everything on for everyone with that rank and only for that person. Or there's occasionally one of my own friends that has obnoxious effects on their model, I don't want to have to turn everything off for all my friends... only that one person.
Being able to adjust these settings by individual would greatly help these situations.