I went to an erotic art show in Cardiff some years back. There was a 'Sex Chair' on show, hand carved to a very elaborate design, it had sticky bitseverywhere with endless ties downs. The lady I was with, being a bit of an exhibitionist, was climbing all over it, I wish I'dhad a camera with me.
Amazon does have a selection of fun looking things;
External Link/Members OnlyGoogle Images for 'sex chair' is an eye opener;
Hidden Image/Members Only