Eyebrow wax. I recommend Ben Nye, but any theatrical makeup vendor will do. Do not use one of those cheapy Halloween kits that are out now -- pay for the real stuff. Any year-round, actual costume shop should sell it -- there should be plenty in San Fran.

I second the Ben Nye wax. I've seen some Youtube vids where they use a glue stick and powder, but I've never tried this....

If you can find a copy of "Making Faces" by Kevyn Aucoin, on page 28, there is a tutorial on how to do this using 'sealing wax', a liquid sealer and then concealer and powder. It's a good book to own anyway ;)

the wax is awesome if you have coarser brows that dont want to lay flat. otherwise you can use a glue stick to do it. Run you brow over backwards with the glue stick to get it sticky underneath then the other way to lay em flat. Comb down if needed then smooth down with a spatula (or the side of your tweezers or a smooth butter knife). Let it dry, then if you need more smoothing, take off a chunk of the glue stick and smear it over your flattened brow THICK and smooth it down too. When it dry's powder it lightly then you need a heavy duty concealer. Dermablend works amazingly for this (you can try and talk your way into a small sample at a macys counter maybe?) powder that lightly and you should be good to go with foundation.

The same procedure is pretty much done for wax but you need a spray sealant afterwards and if you really want it to last seal it at the very end with liquid latex.

You can use soap by lathering up an eyebrow brush and combing it through and mashing it flat.

If you find that your concealer isnt heavy enough to cover the color, try a salmon tinted concealer (under eye concealer) or a little bit of red (blush or eyeshadow) to cancel out some of the color under your concealer.

It takes practice for sure... Theres a few youtube videos on it too.