Use a knife to scrape the seeds of the vanilla bean into the cup and stir well. (epicurious.com)
Another option might be to make vanilla brown sugar by putting the brown sugar in an airtight container for a couple days first along with the seeds of a vanilla bean. (davidlebovitz.com)
Scrape out the seeds of the vanilla bean into the mixture and toss in the empty pod. (spachethespatula.com)