For the makers of e-book readers, the raincoater audience — the straightish men who frequent adult bookstores for the promise of a little action in the back — are an unlikely market. They're not even there to read, for starters. But for literate smut fans, who have been choosing Amazon.com from the first day they made erotic books available in discreet, brown-wrapped boxes? If they're turning to the Kindle to deliver their porn, Amazon's not telling. Not entirely. We've got numbers on how well the same books sell in print, but not for their Kindle counterparts. Better figures might be possible if everyone's who's spindled their Kindle dropped Amazon a line.