Who is the bankruptcy trustee? Basically.......
A chapter 7 bankruptcy trustee reviews your chapter 7 bankruptcy, making sure everything is in order, and liquidates the eligible assets of your estate. But, as I have stated before, the liquidation of assets is not that common so don't freak out. This bankruptcy trustee also presides over the 341 hearing (meeting of the creditors--more about that later).
If you have a simple chapter "no-asset" case, you won't have much dealings with the bankruptcy trustee. I saw mine only at the 341 hearing and he asked me questions for less than five minutes.
A chapter 13 bankruptcy will review your chapter 13 bankruptcy, and determine a payment plan for you, ensuring that you will be able to meet your obligations under the plan. He will oversee this payment plan for it's duration.
It sounds intimidating but really, if your bankruptcy is on the up and up, you shouldn't have to worry about the bankruptcy trustee. Bankruptcy is not as scary as you've been led to believe.
Good luck to you!