I'll point in admiration at the Mark Twain Project, released in beta today. I stumbled across this little quote from a letter of October 1865, in a mere 10 minutes of browsing:

P. S. You had better shove this in the stove—for if we strike a bargain I don’t want any absurd “literary remains” & “unpublished letters of Mark Twain” published after I am planted.

Oh, well.