Having the option to set your "My Documents" folder to be your DropBox folder (without resorting to symlinks or toher trickery) might be a cool option to have,

Having the option to set your "My Documents" folder to be your DropBox folder (without resorting to symlinks or toher trickery) might be a cool option to have, but IMHO defaulting to sharing your "My Documents" folder would be highly intrusive and rather evil. Very un-dropbox like. One of the things I love about Dropbox is that they've always seemed to be very straight forward and above board. They feel trustable.