I wouldn't want to see anyone's attempt at a sequel to BK, except Dostoyevsky himself.
I recentely saw something by Dostoyevsky called 'The Diary of a Writer' on Ebay. I didn't know anything about it, so I didn't get it, but I know feel I should've gotten it.
Link:
http://www.utoronto.ca/tsq/DS/09/091.shtml