I just stumbled on a link to a file share site that has a zip folder you can download with 30 e-books on sex topics like anal, oral, kissing, positions, tantra, penis enlargement etc etc. I've downloaded it and it's cosher, but I cant rate the content yet as I've not read it apart from the Kama Sutra ebook. There are no viruses and it's all in pdf format.
Here's the link for fellow OA members - share and enjoy :-)
(you don't need to pay anything, it's free - type in the security numbers and click "free" at the bottom of the page)