I have black(ish) eyebrows they're not super dark or anything but I fill them in with MAC's Spiked eyebrow pencil and Embark eyeshadow. I've used Espresso before and thought it was a little too dark for my tastes. I want to try Mystery though because sometimes I think Embark is too dark -- a little red but then again I used to have dark red/brown highlights in my hair and it looked good, so I think Mystery might be better for me.
If your hair (eyebrows and the hair ontop of your head) is super, super dark and those don't work, you could use Carbon. I've seen girls (MAs at local counters/stores -- and girlies on here and LJ) use Carbon with a light hand and I think it looks good. I guess it depends on the amount of pressure you use and the brush.
I have some black eyebrows and I don't feel them in with nething because they're so thick but my cousin fills her brows in with blacktrack. It doesn't look scary or anything but I guess it depends on the person's face and their hair and how you apply the blacktrack.
I also used Mystery when my brows were dark. I read somewhere if your hair is black your brows should be a tiny bit lighter and Mystery was great b/c it didn't make them look too harsh. I think Carbon will look too harsh.
If your brows are actually black, why not use a eye brow pencil instead of a shadow? Try Spiked or Veveltone. I think its a better alternative than eye shadow, personally.
my brows are jet black - and there's a spot on my right brow that needs filling because hair wont grow in that one spot. I usually just take a dark eye pencil from hot topic, or I use maybelline's unstoppable pencil because it wont smudge! :]
thoguh many people witgh black brows fill with mystery [brown], i prefer to keep my eyebrows natural looking.. i dont want black/brown brows since i have black black hair (im asian).. so i use a gray shadow, which isnt too overpowering or unnatural looking
Another Brun user. I keep trying other products but I always go back to Brun. Another trick I use is that if I'm using Blacktrack to line my eyes, the residual product on the brush is great for brows. It's just enough to fill in without making you look like Morticia.