Don't just leave it! You have to wrap her hoof. ;)
Wrap it with a drawing salve, or if she's turned out 24/7, soak her hoof for 15 minutes in a tub/bucket full of warm water and epson salt, twice (or once, if twice isn't feasible) a day. This will help pull the bruise to the sole instead of up, and it will help it come out faster. Most of the time, it's really worth it to call the farrier as they will 'cut it out'.
If you decide to soak, don't be alarmed if she seems to get a LOT worse--it gets painful for them! I would put her in a stall if possible.