I know apple run a pretty tight ship regarding 'adult' content, but I have found a few good apps and wanted if anyone else can share their findings. No doubt this has already been done as a topic, but no harm in having updated list!
My findings are a few karma sutra apps, not bad considering they were few. also have a truth and dare app, and an 'adult game' with various forfeits such as swapping underwear with another member of the party, to saying you ultimate fantasy out loud.
I don't know of many. I know that a few kinky Models have apps and skirt around Apple's rules by billing themselves as 'Lifestyle' apps.
I make iPhone and iPad apps for a living, and while I haven't made any adult apps, the AppStore can be a tricky place to navigate as a developer... I'm not surprised there aren't many.