I just shot a VERY informal gathering, and for one dining table image, in portrait format, I forgot to rotate the SB900 sideways so it was still pointing at the ceiling. So it was pointing catywampus directly at the table.
As a result, a person at the close end of the table was blown sky high, and the person across the table from her was literally in the dark.
The JPG was hopeless --- no way to get enough data out of it (except for a few people half way down the table).
The RAW file was a totally different thing. With judicious use of "Shadows" and "Highlights" in Adobe Camera RAW, I was able to pull the poor guy out of the dark, and the young lady down to looking almost fully alive. Good enough for the informal results and web page.