Founded on
April 1, 1967, the NTSB's
primary mission is investigating
civil aviation mishaps and recording and maintaining them in a
government database. The NTSB is only called on to investigate accidents and issues for other modes of transportation when they are
significant in nature.
Although it has no regulatory or enforcement powers, the NTSB is frequently called upon to make recommendations towards improving transportation safety and preventing future accidents. As a matter of fact, 80% of its advice has been taken by those who could make the changes. On a smaller scale, the NTSB serves as an "appeals court" when an airman, mariner, or related mechanic has had an action taken upon them by the FAA or the US Coast Guard Commandant.
And yes, if you are fiending for some gore to read, check out their website. For fun, you can count how many small aircraft pilots have flown into the sides of mountains -- Just make sure you're not eating anything red at the time.